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This is the hard version of this problem. The difference between easy and hard versions is only the constraints on $$$a_i$$$ and on $$$n$$$. You can make hacks only if both versions of the problem are solved.Burenka is the crown princess of Buryatia, and soon she will become the $$$n$$$-th queen of the country. There is an ancient tradition in Buryatia — before the coronation, the ruler must show their strength to the inhabitants. To determine the strength of the $$$n$$$-th ruler, the inhabitants of the country give them an array of $$$a$$$ of exactly $$$n$$$ numbers, after which the ruler must turn all the elements of the array into zeros in the shortest time. The ruler can do the following two-step operation any number of times: select two indices $$$l$$$ and $$$r$$$, so that $$$1 \le l \le r \le n$$$ and a non-negative integer $$$x$$$, then for all $$$l \leq i \leq r$$$ assign $$$a_i := a_i \oplus x$$$, where $$$\oplus$$$ denotes the bitwise XOR operation. It takes $$$\left\lceil \frac{r-l+1}{2} \right\rceil$$$ seconds to do this operation, where $$$\lceil y \rceil$$$ denotes $$$y$$$ rounded up to the nearest integer. Help Burenka calculate how much time she will need. | [] |
Peter has a sequence of integers a1, a2, ..., an. Peter wants all numbers in the sequence to equal h. He can perform the operation of "adding one on the segment [l, r]": add one to all elements of the sequence with indices from l to r (inclusive). At that, Peter never chooses any element as the beginning of the segment twice. Similarly, Peter never chooses any element as the end of the segment twice. In other words, for any two segments [l1, r1] and [l2, r2], where Peter added one, the following inequalities hold: l1 ≠ l2 and r1 ≠ r2.How many distinct ways are there to make all numbers in the sequence equal h? Print this number of ways modulo 1000000007 (109 + 7). Two ways are considered distinct if one of them has a segment that isn't in the other way. | [] |
The Smart Beaver from ABBYY has once again surprised us! He has developed a new calculating device, which he called the "Beaver's Calculator 1.0". It is very peculiar and it is planned to be used in a variety of scientific problems.To test it, the Smart Beaver invited n scientists, numbered from 1 to n. The i-th scientist brought ki calculating problems for the device developed by the Smart Beaver from ABBYY. The problems of the i-th scientist are numbered from 1 to ki, and they must be calculated sequentially in the described order, since calculating each problem heavily depends on the results of calculating of the previous ones.Each problem of each of the n scientists is described by one integer ai, j, where i (1 ≤ i ≤ n) is the number of the scientist, j (1 ≤ j ≤ ki) is the number of the problem, and ai, j is the number of resource units the calculating device needs to solve this problem.The calculating device that is developed by the Smart Beaver is pretty unusual. It solves problems sequentially, one after another. After some problem is solved and before the next one is considered, the calculating device allocates or frees resources.The most expensive operation for the calculating device is freeing resources, which works much slower than allocating them. It is therefore desirable that each next problem for the calculating device requires no less resources than the previous one.You are given the information about the problems the scientists offered for the testing. You need to arrange these problems in such an order that the number of adjacent "bad" pairs of problems in this list is minimum possible. We will call two consecutive problems in this list a "bad pair" if the problem that is performed first requires more resources than the one that goes after it. Do not forget that the problems of the same scientist must be solved in a fixed order. | [] |
These days Arkady works as an air traffic controller at a large airport. He controls a runway which is usually used for landings only. Thus, he has a schedule of planes that are landing in the nearest future, each landing lasts $$$1$$$ minute.He was asked to insert one takeoff in the schedule. The takeoff takes $$$1$$$ minute itself, but for safety reasons there should be a time space between the takeoff and any landing of at least $$$s$$$ minutes from both sides.Find the earliest time when Arkady can insert the takeoff. | [] |
In this task, Nastya asked us to write a formal statement.An array $$$a$$$ of length $$$n$$$ and an array $$$k$$$ of length $$$n-1$$$ are given. Two types of queries should be processed: increase $$$a_i$$$ by $$$x$$$. Then if $$$a_{i+1} < a_i + k_i$$$, $$$a_{i+1}$$$ becomes exactly $$$a_i + k_i$$$; again, if $$$a_{i+2} < a_{i+1} + k_{i+1}$$$, $$$a_{i+2}$$$ becomes exactly $$$a_{i+1} + k_{i+1}$$$, and so far for $$$a_{i+3}$$$, ..., $$$a_n$$$; print the sum of the contiguous subarray from the $$$l$$$-th element to the $$$r$$$-th element of the array $$$a$$$. It's guaranteed that initially $$$a_i + k_i \leq a_{i+1}$$$ for all $$$1 \leq i \leq n-1$$$. | [] |
Cowboy Vlad has a birthday today! There are $$$n$$$ children who came to the celebration. In order to greet Vlad, the children decided to form a circle around him. Among the children who came, there are both tall and low, so if they stand in a circle arbitrarily, it may turn out, that there is a tall and low child standing next to each other, and it will be difficult for them to hold hands. Therefore, children want to stand in a circle so that the maximum difference between the growth of two neighboring children would be minimal possible.Formally, let's number children from $$$1$$$ to $$$n$$$ in a circle order, that is, for every $$$i$$$ child with number $$$i$$$ will stand next to the child with number $$$i+1$$$, also the child with number $$$1$$$ stands next to the child with number $$$n$$$. Then we will call the discomfort of the circle the maximum absolute difference of heights of the children, who stand next to each other.Please help children to find out how they should reorder themselves, so that the resulting discomfort is smallest possible. | [] |
Once upon a time, Oolimry saw a suffix array. He wondered how many strings can produce this suffix array. More formally, given a suffix array of length $$$n$$$ and having an alphabet size $$$k$$$, count the number of strings that produce such a suffix array. Let $$$s$$$ be a string of length $$$n$$$. Then the $$$i$$$-th suffix of $$$s$$$ is the substring $$$s[i \ldots n-1]$$$. A suffix array is the array of integers that represent the starting indexes of all the suffixes of a given string, after the suffixes are sorted in the lexicographic order. For example, the suffix array of oolimry is $$$[3,2,4,1,0,5,6]$$$ as the array of sorted suffixes is $$$[\texttt{imry},\texttt{limry},\texttt{mry},\texttt{olimry},\texttt{oolimry},\texttt{ry},\texttt{y}]$$$. A string $$$x$$$ is lexicographically smaller than string $$$y$$$, if either $$$x$$$ is a prefix of $$$y$$$ (and $$$x\neq y$$$), or there exists such $$$i$$$ that $$$x_i < y_i$$$, and for any $$$1\leq j < i$$$ , $$$x_j = y_j$$$. | ['math'] |
Today the «Z» city residents enjoy a shell game competition. The residents are gathered on the main square to watch the breath-taking performance. The performer puts 3 non-transparent cups upside down in a row. Then he openly puts a small ball under one of the cups and starts to shuffle the cups around very quickly so that on the whole he makes exactly 3 shuffles. After that the spectators have exactly one attempt to guess in which cup they think the ball is and if the answer is correct they get a prize. Maybe you can try to find the ball too? | [] |
You are given a tree consisting of $$$n$$$ vertices. A number is written on each vertex; the number on vertex $$$i$$$ is equal to $$$a_i$$$.Let's denote the function $$$g(x, y)$$$ as the greatest common divisor of the numbers written on the vertices belonging to the simple path from vertex $$$x$$$ to vertex $$$y$$$ (including these two vertices). Also let's denote $$$dist(x, y)$$$ as the number of vertices on the simple path between vertices $$$x$$$ and $$$y$$$, including the endpoints. $$$dist(x, x) = 1$$$ for every vertex $$$x$$$.Your task is calculate the maximum value of $$$dist(x, y)$$$ among such pairs of vertices that $$$g(x, y) > 1$$$. | ['number theory', 'trees'] |
You are given $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$. Each of $$$a_i$$$ has between $$$3$$$ and $$$5$$$ divisors. Consider $$$a = \prod a_i$$$ — the product of all input integers. Find the number of divisors of $$$a$$$. As this number may be very large, print it modulo prime number $$$998244353$$$. | ['math', 'number theory'] |
Anton likes to play chess. Also he likes to do programming. No wonder that he decided to attend chess classes and programming classes.Anton has n variants when he will attend chess classes, i-th variant is given by a period of time (l1, i, r1, i). Also he has m variants when he will attend programming classes, i-th variant is given by a period of time (l2, i, r2, i).Anton needs to choose exactly one of n possible periods of time when he will attend chess classes and exactly one of m possible periods of time when he will attend programming classes. He wants to have a rest between classes, so from all the possible pairs of the periods he wants to choose the one where the distance between the periods is maximal.The distance between periods (l1, r1) and (l2, r2) is the minimal possible distance between a point in the first period and a point in the second period, that is the minimal possible |i - j|, where l1 ≤ i ≤ r1 and l2 ≤ j ≤ r2. In particular, when the periods intersect, the distance between them is 0.Anton wants to know how much time his rest between the classes will last in the best case. Help Anton and find this number! | [] |
There are $$$n$$$ houses in your city arranged on an axis at points $$$h_1, h_2, \ldots, h_n$$$. You want to build a new house for yourself and consider two options where to place it: points $$$p_1$$$ and $$$p_2$$$.As you like visiting friends, you have calculated in advance the distances from both options to all existing houses. More formally, you have calculated two arrays $$$d_1$$$, $$$d_2$$$: $$$d_{i, j} = \left|p_i - h_j\right|$$$, where $$$|x|$$$ defines the absolute value of $$$x$$$.After a long time of inactivity you have forgotten the locations of the houses $$$h$$$ and the options $$$p_1$$$, $$$p_2$$$. But your diary still keeps two arrays — $$$d_1$$$, $$$d_2$$$, whose authenticity you doubt. Also, the values inside each array could be shuffled, so values at the same positions of $$$d_1$$$ and $$$d_2$$$ may correspond to different houses. Pay attention, that values from one array could not get to another, in other words, all values in the array $$$d_1$$$ correspond the distances from $$$p_1$$$ to the houses, and in the array $$$d_2$$$ — from $$$p_2$$$ to the houses.Also pay attention, that the locations of the houses $$$h_i$$$ and the considered options $$$p_j$$$ could match. For example, the next locations are correct: $$$h = \{1, 0, 3, 3\}$$$, $$$p = \{1, 1\}$$$, that could correspond to already shuffled $$$d_1 = \{0, 2, 1, 2\}$$$, $$$d_2 = \{2, 2, 1, 0\}$$$.Check whether there are locations of houses $$$h$$$ and considered points $$$p_1$$$, $$$p_2$$$, for which the founded arrays of distances would be correct. If it is possible, find appropriate locations of houses and considered options. | [] |
You are given a 4x4 grid. You play a game — there is a sequence of tiles, each of them is either 2x1 or 1x2. Your task is to consequently place all tiles from the given sequence in the grid. When tile is placed, each cell which is located in fully occupied row or column is deleted (cells are deleted at the same time independently). You can place tile in the grid at any position, the only condition is that tiles (and tile parts) should not overlap. Your goal is to proceed all given figures and avoid crossing at any time. | [] |
Wabbit is trying to move a box containing food for the rest of the zoo in the coordinate plane from the point $$$(x_1,y_1)$$$ to the point $$$(x_2,y_2)$$$.He has a rope, which he can use to pull the box. He can only pull the box if he stands exactly $$$1$$$ unit away from the box in the direction of one of two coordinate axes. He will pull the box to where he is standing before moving out of the way in the same direction by $$$1$$$ unit. For example, if the box is at the point $$$(1,2)$$$ and Wabbit is standing at the point $$$(2,2)$$$, he can pull the box right by $$$1$$$ unit, with the box ending up at the point $$$(2,2)$$$ and Wabbit ending at the point $$$(3,2)$$$.Also, Wabbit can move $$$1$$$ unit to the right, left, up, or down without pulling the box. In this case, it is not necessary for him to be in exactly $$$1$$$ unit away from the box. If he wants to pull the box again, he must return to a point next to the box. Also, Wabbit can't move to the point where the box is located.Wabbit can start at any point. It takes $$$1$$$ second to travel $$$1$$$ unit right, left, up, or down, regardless of whether he pulls the box while moving.Determine the minimum amount of time he needs to move the box from $$$(x_1,y_1)$$$ to $$$(x_2,y_2)$$$. Note that the point where Wabbit ends up at does not matter. | ['math'] |
Suppose you have two points $$$p = (x_p, y_p)$$$ and $$$q = (x_q, y_q)$$$. Let's denote the Manhattan distance between them as $$$d(p, q) = |x_p - x_q| + |y_p - y_q|$$$.Let's say that three points $$$p$$$, $$$q$$$, $$$r$$$ form a bad triple if $$$d(p, r) = d(p, q) + d(q, r)$$$.Let's say that an array $$$b_1, b_2, \dots, b_m$$$ is good if it is impossible to choose three distinct indices $$$i$$$, $$$j$$$, $$$k$$$ such that the points $$$(b_i, i)$$$, $$$(b_j, j)$$$ and $$$(b_k, k)$$$ form a bad triple.You are given an array $$$a_1, a_2, \dots, a_n$$$. Calculate the number of good subarrays of $$$a$$$. A subarray of the array $$$a$$$ is the array $$$a_l, a_{l + 1}, \dots, a_r$$$ for some $$$1 \le l \le r \le n$$$.Note that, according to the definition, subarrays of length $$$1$$$ and $$$2$$$ are good. | ['geometry'] |
There are n balls. They are arranged in a row. Each ball has a color (for convenience an integer) and an integer value. The color of the i-th ball is ci and the value of the i-th ball is vi.Squirrel Liss chooses some balls and makes a new sequence without changing the relative order of the balls. She wants to maximize the value of this sequence.The value of the sequence is defined as the sum of following values for each ball (where a and b are given constants): If the ball is not in the beginning of the sequence and the color of the ball is same as previous ball's color, add (the value of the ball) × a. Otherwise, add (the value of the ball) × b. You are given q queries. Each query contains two integers ai and bi. For each query find the maximal value of the sequence she can make when a = ai and b = bi.Note that the new sequence can be empty, and the value of an empty sequence is defined as zero. | [] |
The All-Berland National Olympiad in Informatics has just ended! Now Vladimir wants to upload the contest from the Olympiad as a gym to a popular Codehorses website.Unfortunately, the archive with Olympiad's data is a mess. For example, the files with tests are named arbitrary without any logic.Vladimir wants to rename the files with tests so that their names are distinct integers starting from 1 without any gaps, namely, "1", "2", ..., "n', where n is the total number of tests.Some of the files contain tests from statements (examples), while others contain regular tests. It is possible that there are no examples, and it is possible that all tests are examples. Vladimir wants to rename the files so that the examples are the first several tests, all all the next files contain regular tests only.The only operation Vladimir can perform is the "move" command. Vladimir wants to write a script file, each of the lines in which is "move file_1 file_2", that means that the file "file_1" is to be renamed to "file_2". If there is a file "file_2" at the moment of this line being run, then this file is to be rewritten. After the line "move file_1 file_2" the file "file_1" doesn't exist, but there is a file "file_2" with content equal to the content of "file_1" before the "move" command.Help Vladimir to write the script file with the minimum possible number of lines so that after this script is run: all examples are the first several tests having filenames "1", "2", ..., "e", where e is the total number of examples; all other files contain regular tests with filenames "e + 1", "e + 2", ..., "n", where n is the total number of all tests. | [] |
When Darth Vader gets bored, he sits down on the sofa, closes his eyes and thinks of an infinite rooted tree where each node has exactly n sons, at that for each node, the distance between it an its i-th left child equals to di. The Sith Lord loves counting the number of nodes in the tree that are at a distance at most x from the root. The distance is the sum of the lengths of edges on the path between nodes.But he has got used to this activity and even grew bored of it. 'Why does he do that, then?' — you may ask. It's just that he feels superior knowing that only he can solve this problem. Do you want to challenge Darth Vader himself? Count the required number of nodes. As the answer can be rather large, find it modulo 109 + 7. | [] |
Vasya is pressing the keys on the keyboard reluctantly, squeezing out his ideas on the classical epos depicted in Homer's Odysseus... How can he explain to his literature teacher that he isn't going to become a writer? In fact, he is going to become a programmer. So, he would take great pleasure in writing a program, but none — in writing a composition.As Vasya was fishing for a sentence in the dark pond of his imagination, he suddenly wondered: what is the least number of times he should push a key to shift the cursor from one position to another one?Let's describe his question more formally: to type a text, Vasya is using the text editor. He has already written n lines, the i-th line contains ai characters (including spaces). If some line contains k characters, then this line overall contains (k + 1) positions where the cursor can stand: before some character or after all characters (at the end of the line). Thus, the cursor's position is determined by a pair of integers (r, c), where r is the number of the line and c is the cursor's position in the line (the positions are indexed starting from one from the beginning of the line).Vasya doesn't use the mouse to move the cursor. He uses keys "Up", "Down", "Right" and "Left". When he pushes each of these keys, the cursor shifts in the needed direction. Let's assume that before the corresponding key is pressed, the cursor was located in the position (r, c), then Vasya pushed key: "Up": if the cursor was located in the first line (r = 1), then it does not move. Otherwise, it moves to the previous line (with number r - 1), to the same position. At that, if the previous line was short, that is, the cursor couldn't occupy position c there, the cursor moves to the last position of the line with number r - 1; "Down": if the cursor was located in the last line (r = n), then it does not move. Otherwise, it moves to the next line (with number r + 1), to the same position. At that, if the next line was short, that is, the cursor couldn't occupy position c there, the cursor moves to the last position of the line with number r + 1; "Right": if the cursor can move to the right in this line (c < ar + 1), then it moves to the right (to position c + 1). Otherwise, it is located at the end of the line and doesn't move anywhere when Vasya presses the "Right" key; "Left": if the cursor can move to the left in this line (c > 1), then it moves to the left (to position c - 1). Otherwise, it is located at the beginning of the line and doesn't move anywhere when Vasya presses the "Left" key.You've got the number of lines in the text file and the number of characters, written in each line of this file. Find the least number of times Vasya should push the keys, described above, to shift the cursor from position (r1, c1) to position (r2, c2). | ['graphs'] |
The well-known Fibonacci sequence $$$F_0, F_1, F_2,\ldots $$$ is defined as follows: $$$F_0 = 0, F_1 = 1$$$. For each $$$i \geq 2$$$: $$$F_i = F_{i - 1} + F_{i - 2}$$$. Given an increasing arithmetic sequence of positive integers with $$$n$$$ elements: $$$(a, a + d, a + 2\cdot d,\ldots, a + (n - 1)\cdot d)$$$.You need to find another increasing arithmetic sequence of positive integers with $$$n$$$ elements $$$(b, b + e, b + 2\cdot e,\ldots, b + (n - 1)\cdot e)$$$ such that: $$$0 < b, e < 2^{64}$$$, for all $$$0\leq i < n$$$, the decimal representation of $$$a + i \cdot d$$$ appears as substring in the last $$$18$$$ digits of the decimal representation of $$$F_{b + i \cdot e}$$$ (if this number has less than $$$18$$$ digits, then we consider all its digits). | ['number theory'] |
It was recycling day in Kekoland. To celebrate it Adil and Bera went to Central Perk where they can take bottles from the ground and put them into a recycling bin.We can think Central Perk as coordinate plane. There are n bottles on the ground, the i-th bottle is located at position (xi, yi). Both Adil and Bera can carry only one bottle at once each. For both Adil and Bera the process looks as follows: Choose to stop or to continue to collect bottles. If the choice was to continue then choose some bottle and walk towards it. Pick this bottle and walk to the recycling bin. Go to step 1. Adil and Bera may move independently. They are allowed to pick bottles simultaneously, all bottles may be picked by any of the two, it's allowed that one of them stays still while the other one continues to pick bottles.They want to organize the process such that the total distance they walk (the sum of distance walked by Adil and distance walked by Bera) is minimum possible. Of course, at the end all bottles should lie in the recycling bin. | ['geometry'] |
The administration of the Tomsk Region firmly believes that it's time to become a megacity (that is, get population of one million). Instead of improving the demographic situation, they decided to achieve its goal by expanding the boundaries of the city.The city of Tomsk can be represented as point on the plane with coordinates (0; 0). The city is surrounded with n other locations, the i-th one has coordinates (xi, yi) with the population of ki people. You can widen the city boundaries to a circle of radius r. In such case all locations inside the circle and on its border are included into the city.Your goal is to write a program that will determine the minimum radius r, to which is necessary to expand the boundaries of Tomsk, so that it becomes a megacity. | [] |
You are given an array $$$a$$$ consisting of $$$n$$$ positive integers, and an array $$$b$$$, with length $$$n$$$. Initially $$$b_i=0$$$ for each $$$1 \leq i \leq n$$$.In one move you can choose an integer $$$i$$$ ($$$1 \leq i \leq n$$$), and add $$$a_i$$$ to $$$b_i$$$ or subtract $$$a_i$$$ from $$$b_i$$$. What is the minimum number of moves needed to make $$$b$$$ increasing (that is, every element is strictly greater than every element before it)? | ['math'] |
Every December, VK traditionally holds an event for its employees named "Secret Santa". Here's how it happens.$$$n$$$ employees numbered from $$$1$$$ to $$$n$$$ take part in the event. Each employee $$$i$$$ is assigned a different employee $$$b_i$$$, to which employee $$$i$$$ has to make a new year gift. Each employee is assigned to exactly one other employee, and nobody is assigned to themselves (but two employees may be assigned to each other). Formally, all $$$b_i$$$ must be distinct integers between $$$1$$$ and $$$n$$$, and for any $$$i$$$, $$$b_i \ne i$$$ must hold.The assignment is usually generated randomly. This year, as an experiment, all event participants have been asked who they wish to make a gift to. Each employee $$$i$$$ has said that they wish to make a gift to employee $$$a_i$$$.Find a valid assignment $$$b$$$ that maximizes the number of fulfilled wishes of the employees. | ['math', 'graphs'] |
In all schools in Buryatia, in the $$$1$$$ class, everyone is told the theory of Fibonacci strings."A block is a subsegment of a string where all the letters are the same and are bounded on the left and right by the ends of the string or by letters other than the letters in the block. A string is called a Fibonacci string if, when it is divided into blocks, their lengths in the order they appear in the string form the Fibonacci sequence ($$$f_0 = f_1 = 1$$$, $$$f_i = f_{i-2} + f_{i-1}$$$), starting from the zeroth member of this sequence. A string is called semi-Fibonacci if it possible to reorder its letters to get a Fibonacci string."Burenka decided to enter the Buryat State University, but at the entrance exam she was given a difficult task. She was given a string consisting of the letters of the Buryat alphabet (which contains exactly $$$k$$$ letters), and was asked if the given string is semi-Fibonacci. The string can be very long, so instead of the string, she was given the number of appearances of each letter ($$$c_i$$$ for the $$$i$$$-th letter) in that string. Unfortunately, Burenka no longer remembers the theory of Fibonacci strings, so without your help she will not pass the exam. | ['math', 'number theory'] |
You are given a string $$$s$$$ of even length $$$n$$$. String $$$s$$$ is binary, in other words, consists only of 0's and 1's.String $$$s$$$ has exactly $$$\frac{n}{2}$$$ zeroes and $$$\frac{n}{2}$$$ ones ($$$n$$$ is even).In one operation you can reverse any substring of $$$s$$$. A substring of a string is a contiguous subsequence of that string.What is the minimum number of operations you need to make string $$$s$$$ alternating? A string is alternating if $$$s_i \neq s_{i + 1}$$$ for all $$$i$$$. There are two types of alternating strings in general: 01010101... or 10101010... | [] |
Fifa and Fafa are sharing a flat. Fifa loves video games and wants to download a new soccer game. Unfortunately, Fafa heavily uses the internet which consumes the quota. Fifa can access the internet through his Wi-Fi access point. This access point can be accessed within a range of r meters (this range can be chosen by Fifa) from its position. Fifa must put the access point inside the flat which has a circular shape of radius R. Fifa wants to minimize the area that is not covered by the access point inside the flat without letting Fafa or anyone outside the flat to get access to the internet.The world is represented as an infinite 2D plane. The flat is centered at (x1, y1) and has radius R and Fafa's laptop is located at (x2, y2), not necessarily inside the flat. Find the position and the radius chosen by Fifa for his access point which minimizes the uncovered area. | ['geometry'] |
— Oh my sweet Beaverette, would you fancy a walk along a wonderful woodland belt with me? — Of course, my Smart Beaver! Let us enjoy the splendid view together. How about Friday night? At this point the Smart Beaver got rushing. Everything should be perfect by Friday, so he needed to prepare the belt to the upcoming walk. He needed to cut down several trees.Let's consider the woodland belt as a sequence of trees. Each tree i is described by the esthetic appeal ai — some trees are very esthetically pleasing, others are 'so-so', and some trees are positively ugly!The Smart Beaver calculated that he needed the following effects to win the Beaverette's heart: The first objective is to please the Beaverette: the sum of esthetic appeal of the remaining trees must be maximum possible; the second objective is to surprise the Beaverette: the esthetic appeal of the first and the last trees in the resulting belt must be the same; and of course, the walk should be successful: there must be at least two trees in the woodland belt left. Now help the Smart Beaver! Which trees does he need to cut down to win the Beaverette's heart? | [] |
It is the middle of 2018 and Maria Stepanovna, who lives outside Krasnokamensk (a town in Zabaikalsky region), wants to rent three displays to highlight an important problem.There are $$$n$$$ displays placed along a road, and the $$$i$$$-th of them can display a text with font size $$$s_i$$$ only. Maria Stepanovna wants to rent such three displays with indices $$$i < j < k$$$ that the font size increases if you move along the road in a particular direction. Namely, the condition $$$s_i < s_j < s_k$$$ should be held.The rent cost is for the $$$i$$$-th display is $$$c_i$$$. Please determine the smallest cost Maria Stepanovna should pay. | [] |
There are $$$n$$$ persons who initially don't know each other. On each morning, two of them, who were not friends before, become friends.We want to plan a trip for every evening of $$$m$$$ days. On each trip, you have to select a group of people that will go on the trip. For every person, one of the following should hold: Either this person does not go on the trip, Or at least $$$k$$$ of his friends also go on the trip. Note that the friendship is not transitive. That is, if $$$a$$$ and $$$b$$$ are friends and $$$b$$$ and $$$c$$$ are friends, it does not necessarily imply that $$$a$$$ and $$$c$$$ are friends.For each day, find the maximum number of people that can go on the trip on that day. | ['graphs'] |
Berlanders like to eat cones after a hard day. Misha Square and Sasha Circle are local authorities of Berland. Each of them controls its points of cone trade. Misha has n points, Sasha — m. Since their subordinates constantly had conflicts with each other, they decided to build a fence in the form of a circle, so that the points of trade of one businessman are strictly inside a circle, and points of the other one are strictly outside. It doesn't matter which of the two gentlemen will have his trade points inside the circle.Determine whether they can build a fence or not. | ['math', 'geometry'] |
IA has so many colorful magnets on her fridge! Exactly one letter is written on each magnet, 'a' or 'b'. She loves to play with them, placing all magnets in a row. However, the girl is quickly bored and usually thinks how to make her entertainment more interesting.Today, when IA looked at the fridge, she noticed that the word formed by magnets is really messy. "It would look much better when I'll swap some of them!" — thought the girl — "but how to do it?". After a while, she got an idea. IA will look at all prefixes with lengths from $$$1$$$ to the length of the word and for each prefix she will either reverse this prefix or leave it as it is. She will consider the prefixes in the fixed order: from the shortest to the largest. She wants to get the lexicographically smallest possible word after she considers all prefixes. Can you help her, telling which prefixes should be chosen for reversing?A string $$$a$$$ is lexicographically smaller than a string $$$b$$$ if and only if one of the following holds: $$$a$$$ is a prefix of $$$b$$$, but $$$a \ne b$$$; in the first position where $$$a$$$ and $$$b$$$ differ, the string $$$a$$$ has a letter that appears earlier in the alphabet than the corresponding letter in $$$b$$$. | [] |
You can perfectly predict the price of a certain stock for the next N days. You would like to profit on this knowledge, but only want to transact one share of stock per day. That is, each day you will either buy one share, sell one share, or do nothing. Initially you own zero shares, and you cannot sell shares when you don't own any. At the end of the N days you would like to again own zero shares, but want to have as much money as possible. | [] |
Ivan places knights on infinite chessboard. Initially there are $$$n$$$ knights. If there is free cell which is under attack of at least $$$4$$$ knights then he places new knight in this cell. Ivan repeats this until there are no such free cells. One can prove that this process is finite. One can also prove that position in the end does not depend on the order in which new knights are placed.Ivan asked you to find initial placement of exactly $$$n$$$ knights such that in the end there will be at least $$$\lfloor \frac{n^{2}}{10} \rfloor$$$ knights. | [] |
Kawasiro Nitori is excellent in engineering. Thus she has been appointed to help maintain trains.There are $$$n$$$ models of trains, and Nitori's department will only have at most one train of each model at any moment. In the beginning, there are no trains, at each of the following $$$m$$$ days, one train will be added, or one train will be removed. When a train of model $$$i$$$ is added at day $$$t$$$, it works for $$$x_i$$$ days (day $$$t$$$ inclusive), then it is in maintenance for $$$y_i$$$ days, then in work for $$$x_i$$$ days again, and so on until it is removed.In order to make management easier, Nitori wants you to help her calculate how many trains are in maintenance in each day.On a day a train is removed, it is not counted as in maintenance. | [] |
Roman and Denis are on the trip to the programming competition. Since the trip was long, they soon got bored, and hence decided to came up with something. Roman invented a pizza's recipe, while Denis invented a string multiplication. According to Denis, the result of multiplication (product) of strings $$$s$$$ of length $$$m$$$ and $$$t$$$ is a string $$$t + s_1 + t + s_2 + \ldots + t + s_m + t$$$, where $$$s_i$$$ denotes the $$$i$$$-th symbol of the string $$$s$$$, and "+" denotes string concatenation. For example, the product of strings "abc" and "de" is a string "deadebdecde", while the product of the strings "ab" and "z" is a string "zazbz". Note, that unlike the numbers multiplication, the product of strings $$$s$$$ and $$$t$$$ is not necessarily equal to product of $$$t$$$ and $$$s$$$.Roman was jealous of Denis, since he invented such a cool operation, and hence decided to invent something string-related too. Since Roman is beauty-lover, he decided to define the beauty of the string as the length of the longest substring, consisting of only one letter. For example, the beauty of the string "xayyaaabca" is equal to $$$3$$$, since there is a substring "aaa", while the beauty of the string "qwerqwer" is equal to $$$1$$$, since all neighboring symbols in it are different.In order to entertain Roman, Denis wrote down $$$n$$$ strings $$$p_1, p_2, p_3, \ldots, p_n$$$ on the paper and asked him to calculate the beauty of the string $$$( \ldots (((p_1 \cdot p_2) \cdot p_3) \cdot \ldots ) \cdot p_n$$$, where $$$s \cdot t$$$ denotes a multiplication of strings $$$s$$$ and $$$t$$$. Roman hasn't fully realized how Denis's multiplication works, so he asked you for a help. Denis knows, that Roman is very impressionable, he guarantees, that the beauty of the resulting string is at most $$$10^9$$$. | ['strings'] |
The only difference between the easy and hard versions is the constraints on the number of queries.This is an interactive problem.Ridbit has a hidden array $$$a$$$ of $$$n$$$ integers which he wants Ashish to guess. Note that $$$n$$$ is a power of two. Ashish is allowed to ask three different types of queries. They are of the form AND $$$i$$$ $$$j$$$: ask for the bitwise AND of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$ OR $$$i$$$ $$$j$$$: ask for the bitwise OR of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$ XOR $$$i$$$ $$$j$$$: ask for the bitwise XOR of elements $$$a_i$$$ and $$$a_j$$$ $$$(1 \leq i, j \le n$$$, $$$i \neq j)$$$ Can you help Ashish guess the elements of the array?In this version, each element takes a value in the range $$$[0, n-1]$$$ (inclusive) and Ashish can ask no more than $$$n+2$$$ queries. | ['math'] |
The stardate is 1983, and Princess Heidi is getting better at detecting the Death Stars. This time, two Rebel spies have yet again given Heidi two maps with the possible locations of the Death Star. Since she got rid of all double agents last time, she knows that both maps are correct, and indeed show the map of the solar system that contains the Death Star. However, this time the Empire has hidden the Death Star very well, and Heidi needs to find a place that appears on both maps in order to detect the Death Star.The first map is an N × M grid, each cell of which shows some type of cosmic object that is present in the corresponding quadrant of space. The second map is an M × N grid. Heidi needs to align those two maps in such a way that they overlap over some M × M section in which all cosmic objects are identical. Help Heidi by identifying where such an M × M section lies within both maps. | ['strings'] |
A positive (strictly greater than zero) integer is called round if it is of the form d00...0. In other words, a positive integer is round if all its digits except the leftmost (most significant) are equal to zero. In particular, all numbers from $$$1$$$ to $$$9$$$ (inclusive) are round.For example, the following numbers are round: $$$4000$$$, $$$1$$$, $$$9$$$, $$$800$$$, $$$90$$$. The following numbers are not round: $$$110$$$, $$$707$$$, $$$222$$$, $$$1001$$$.You are given a positive integer $$$n$$$ ($$$1 \le n \le 10^4$$$). Represent the number $$$n$$$ as a sum of round numbers using the minimum number of summands (addends). In other words, you need to represent the given number $$$n$$$ as a sum of the least number of terms, each of which is a round number. | ['math'] |
The map of the capital of Berland can be viewed on the infinite coordinate plane. Each point with integer coordinates contains a building, and there are streets connecting every building to four neighbouring buildings. All streets are parallel to the coordinate axes.The main school of the capital is located in $$$(s_x, s_y)$$$. There are $$$n$$$ students attending this school, the $$$i$$$-th of them lives in the house located in $$$(x_i, y_i)$$$. It is possible that some students live in the same house, but no student lives in $$$(s_x, s_y)$$$.After classes end, each student walks from the school to his house along one of the shortest paths. So the distance the $$$i$$$-th student goes from the school to his house is $$$|s_x - x_i| + |s_y - y_i|$$$.The Provision Department of Berland has decided to open a shawarma tent somewhere in the capital (at some point with integer coordinates). It is considered that the $$$i$$$-th student will buy a shawarma if at least one of the shortest paths from the school to the $$$i$$$-th student's house goes through the point where the shawarma tent is located. It is forbidden to place the shawarma tent at the point where the school is located, but the coordinates of the shawarma tent may coincide with the coordinates of the house of some student (or even multiple students).You want to find the maximum possible number of students buying shawarma and the optimal location for the tent itself. | ['geometry'] |
Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.Petya and his friend Vasya play an interesting game. Petya randomly chooses an integer p from the interval [pl, pr] and Vasya chooses an integer v from the interval [vl, vr] (also randomly). Both players choose their integers equiprobably. Find the probability that the interval [min(v, p), max(v, p)] contains exactly k lucky numbers. | ['probabilities'] |
Vanya decided to walk in the field of size n × n cells. The field contains m apple trees, the i-th apple tree is at the cell with coordinates (xi, yi). Vanya moves towards vector (dx, dy). That means that if Vanya is now at the cell (x, y), then in a second he will be at cell . The following condition is satisfied for the vector: , where is the largest integer that divides both a and b. Vanya ends his path when he reaches the square he has already visited. Vanya wonders, from what square of the field he should start his path to see as many apple trees as possible. | ['math'] |
Monocarp had a permutation $$$a$$$ of $$$n$$$ integers $$$1$$$, $$$2$$$, ..., $$$n$$$ (a permutation is an array where each element from $$$1$$$ to $$$n$$$ occurs exactly once).Then Monocarp calculated an array of integers $$$b$$$ of size $$$n$$$, where $$$b_i = \left\lfloor \frac{i}{a_i} \right\rfloor$$$. For example, if the permutation $$$a$$$ is $$$[2, 1, 4, 3]$$$, then the array $$$b$$$ is equal to $$$\left[ \left\lfloor \frac{1}{2} \right\rfloor, \left\lfloor \frac{2}{1} \right\rfloor, \left\lfloor \frac{3}{4} \right\rfloor, \left\lfloor \frac{4}{3} \right\rfloor \right] = [0, 2, 0, 1]$$$.Unfortunately, the Monocarp has lost his permutation, so he wants to restore it. Your task is to find a permutation $$$a$$$ that corresponds to the given array $$$b$$$. If there are multiple possible permutations, then print any of them. The tests are constructed in such a way that least one suitable permutation exists. | ['math'] |
You are given two strings $$$s$$$ and $$$t$$$. In a single move, you can choose any of two strings and delete the first (that is, the leftmost) character. After a move, the length of the string decreases by $$$1$$$. You can't choose a string if it is empty.For example: by applying a move to the string "where", the result is the string "here", by applying a move to the string "a", the result is an empty string "". You are required to make two given strings equal using the fewest number of moves. It is possible that, in the end, both strings will be equal to the empty string, and so, are equal to each other. In this case, the answer is obviously the sum of the lengths of the initial strings.Write a program that finds the minimum number of moves to make two given strings $$$s$$$ and $$$t$$$ equal. | ['strings'] |
An African crossword is a rectangular table n × m in size. Each cell of the table contains exactly one letter. This table (it is also referred to as grid) contains some encrypted word that needs to be decoded.To solve the crossword you should cross out all repeated letters in rows and columns. In other words, a letter should only be crossed out if and only if the corresponding column or row contains at least one more letter that is exactly the same. Besides, all such letters are crossed out simultaneously.When all repeated letters have been crossed out, we should write the remaining letters in a string. The letters that occupy a higher position follow before the letters that occupy a lower position. If the letters are located in one row, then the letter to the left goes first. The resulting word is the answer to the problem.You are suggested to solve an African crossword and print the word encrypted there. | ['strings'] |
A group of n merry programmers celebrate Robert Floyd's birthday. Polucarpus has got an honourable task of pouring Ber-Cola to everybody. Pouring the same amount of Ber-Cola to everybody is really important. In other words, the drink's volume in each of the n mugs must be the same.Polycarpus has already began the process and he partially emptied the Ber-Cola bottle. Now the first mug has a1 milliliters of the drink, the second one has a2 milliliters and so on. The bottle has b milliliters left and Polycarpus plans to pour them into the mugs so that the main equation was fulfilled.Write a program that would determine what volume of the drink Polycarpus needs to add into each mug to ensure that the following two conditions were fulfilled simultaneously: there were b milliliters poured in total. That is, the bottle need to be emptied; after the process is over, the volumes of the drink in the mugs should be equal. | ['math'] |
Multiset —is a set of numbers in which there can be equal elements, and the order of the numbers does not matter. Two multisets are equal when each value occurs the same number of times. For example, the multisets $$$\{2,2,4\}$$$ and $$$\{2,4,2\}$$$ are equal, but the multisets $$$\{1,2,2\}$$$ and $$$\{1,1,2\}$$$ — are not.You are given two multisets $$$a$$$ and $$$b$$$, each consisting of $$$n$$$ integers.In a single operation, any element of the $$$b$$$ multiset can be doubled or halved (rounded down). In other words, you have one of the following operations available for an element $$$x$$$ of the $$$b$$$ multiset: replace $$$x$$$ with $$$x \cdot 2$$$, or replace $$$x$$$ with $$$\lfloor \frac{x}{2} \rfloor$$$ (round down). Note that you cannot change the elements of the $$$a$$$ multiset.See if you can make the multiset $$$b$$$ become equal to the multiset $$$a$$$ in an arbitrary number of operations (maybe $$$0$$$).For example, if $$$n = 4$$$, $$$a = \{4, 24, 5, 2\}$$$, $$$b = \{4, 1, 6, 11\}$$$, then the answer is yes. We can proceed as follows: Replace $$$1$$$ with $$$1 \cdot 2 = 2$$$. We get $$$b = \{4, 2, 6, 11\}$$$. Replace $$$11$$$ with $$$\lfloor \frac{11}{2} \rfloor = 5$$$. We get $$$b = \{4, 2, 6, 5\}$$$. Replace $$$6$$$ with $$$6 \cdot 2 = 12$$$. We get $$$b = \{4, 2, 12, 5\}$$$. Replace $$$12$$$ with $$$12 \cdot 2 = 24$$$. We get $$$b = \{4, 2, 24, 5\}$$$. Got equal multisets $$$a = \{4, 24, 5, 2\}$$$ and $$$b = \{4, 2, 24, 5\}$$$. | ['math', 'number theory'] |
You are given n switches and m lamps. The i-th switch turns on some subset of the lamps. This information is given as the matrix a consisting of n rows and m columns where ai, j = 1 if the i-th switch turns on the j-th lamp and ai, j = 0 if the i-th switch is not connected to the j-th lamp.Initially all m lamps are turned off.Switches change state only from "off" to "on". It means that if you press two or more switches connected to the same lamp then the lamp will be turned on after any of this switches is pressed and will remain its state even if any switch connected to this lamp is pressed afterwards.It is guaranteed that if you push all n switches then all m lamps will be turned on.Your think that you have too many switches and you would like to ignore one of them. Your task is to say if there exists such a switch that if you will ignore (not use) it but press all the other n - 1 switches then all the m lamps will be turned on. | [] |
Alice had a permutation $$$p$$$ of numbers from $$$1$$$ to $$$n$$$. Alice can swap a pair $$$(x, y)$$$ which means swapping elements at positions $$$x$$$ and $$$y$$$ in $$$p$$$ (i.e. swap $$$p_x$$$ and $$$p_y$$$). Alice recently learned her first sorting algorithm, so she decided to sort her permutation in the minimum number of swaps possible. She wrote down all the swaps in the order in which she performed them to sort the permutation on a piece of paper. For example, $$$[(2, 3), (1, 3)]$$$ is a valid swap sequence by Alice for permutation $$$p = [3, 1, 2]$$$ whereas $$$[(1, 3), (2, 3)]$$$ is not because it doesn't sort the permutation. Note that we cannot sort the permutation in less than $$$2$$$ swaps. $$$[(1, 2), (2, 3), (2, 4), (2, 3)]$$$ cannot be a sequence of swaps by Alice for $$$p = [2, 1, 4, 3]$$$ even if it sorts the permutation because $$$p$$$ can be sorted in $$$2$$$ swaps, for example using the sequence $$$[(4, 3), (1, 2)]$$$. Unfortunately, Bob shuffled the sequence of swaps written by Alice.You are given Alice's permutation $$$p$$$ and the swaps performed by Alice in arbitrary order. Can you restore the correct sequence of swaps that sorts the permutation $$$p$$$? Since Alice wrote correct swaps before Bob shuffled them up, it is guaranteed that there exists some order of swaps that sorts the permutation. | ['math', 'graphs', 'trees'] |
Mishka has got n empty boxes. For every i (1 ≤ i ≤ n), i-th box is a cube with side length ai.Mishka can put a box i into another box j if the following conditions are met: i-th box is not put into another box; j-th box doesn't contain any other boxes; box i is smaller than box j (ai < aj). Mishka can put boxes into each other an arbitrary number of times. He wants to minimize the number of visible boxes. A box is called visible iff it is not put into some another box.Help Mishka to determine the minimum possible number of visible boxes! | [] |
Igor the analyst has adopted n little bunnies. As we all know, bunnies love carrots. Thus, Igor has bought a carrot to be shared between his bunnies. Igor wants to treat all the bunnies equally, and thus he wants to cut the carrot into n pieces of equal area. Formally, the carrot can be viewed as an isosceles triangle with base length equal to 1 and height equal to h. Igor wants to make n - 1 cuts parallel to the base to cut the carrot into n pieces. He wants to make sure that all n pieces have the same area. Can you help Igor determine where to cut the carrot so that each piece have equal area? Illustration to the first example. | ['math', 'geometry'] |
ZS the Coder is coding on a crazy computer. If you don't type in a word for a c consecutive seconds, everything you typed disappear! More formally, if you typed a word at second a and then the next word at second b, then if b - a ≤ c, just the new word is appended to other words on the screen. If b - a > c, then everything on the screen disappears and after that the word you have typed appears on the screen.For example, if c = 5 and you typed words at seconds 1, 3, 8, 14, 19, 20 then at the second 8 there will be 3 words on the screen. After that, everything disappears at the second 13 because nothing was typed. At the seconds 14 and 19 another two words are typed, and finally, at the second 20, one more word is typed, and a total of 3 words remain on the screen.You're given the times when ZS the Coder typed the words. Determine how many words remain on the screen after he finished typing everything. | [] |
Blake is a CEO of a large company called "Blake Technologies". He loves his company very much and he thinks that his company should be the best. That is why every candidate needs to pass through the interview that consists of the following problem.We define function f(x, l, r) as a bitwise OR of integers xl, xl + 1, ..., xr, where xi is the i-th element of the array x. You are given two arrays a and b of length n. You need to determine the maximum value of sum f(a, l, r) + f(b, l, r) among all possible 1 ≤ l ≤ r ≤ n. | [] |
You have an image file of size $$$2 \times 2$$$, consisting of $$$4$$$ pixels. Each pixel can have one of $$$26$$$ different colors, denoted by lowercase Latin letters.You want to recolor some of the pixels of the image so that all $$$4$$$ pixels have the same color. In one move, you can choose no more than two pixels of the same color and paint them into some other color (if you choose two pixels, both should be painted into the same color).What is the minimum number of moves you have to make in order to fulfill your goal? | [] |
Seiji Maki doesn't only like to observe relationships being unfolded, he also likes to observe sequences of numbers, especially permutations. Today, he has his eyes on almost sorted permutations.A permutation $$$a_1, a_2, \dots, a_n$$$ of $$$1, 2, \dots, n$$$ is said to be almost sorted if the condition $$$a_{i + 1} \ge a_i - 1$$$ holds for all $$$i$$$ between $$$1$$$ and $$$n - 1$$$ inclusive.Maki is considering the list of all almost sorted permutations of $$$1, 2, \dots, n$$$, given in lexicographical order, and he wants to find the $$$k$$$-th permutation in this list. Can you help him to find such permutation?Permutation $$$p$$$ is lexicographically smaller than a permutation $$$q$$$ if and only if the following holds: in the first position where $$$p$$$ and $$$q$$$ differ, the permutation $$$p$$$ has a smaller element than the corresponding element in $$$q$$$. | [] |
You are playing some computer game. One of its levels puts you in a maze consisting of n lines, each of which contains m cells. Each cell either is free or is occupied by an obstacle. The starting cell is in the row r and column c. In one step you can move one square up, left, down or right, if the target cell is not occupied by an obstacle. You can't move beyond the boundaries of the labyrinth.Unfortunately, your keyboard is about to break, so you can move left no more than x times and move right no more than y times. There are no restrictions on the number of moves up and down since the keys used to move up and down are in perfect condition.Now you would like to determine for each cell whether there exists a sequence of moves that will put you from the starting cell to this particular one. How many cells of the board have this property? | ['graphs'] |
A class of students wrote a multiple-choice test.There are $$$n$$$ students in the class. The test had $$$m$$$ questions, each of them had $$$5$$$ possible answers (A, B, C, D or E). There is exactly one correct answer for each question. The correct answer for question $$$i$$$ worth $$$a_i$$$ points. Incorrect answers are graded with zero points.The students remember what answers they gave on the exam, but they don't know what are the correct answers. They are very optimistic, so they want to know what is the maximum possible total score of all students in the class. | ['strings'] |
Innokenty works at a flea market and sells some random stuff rare items. Recently he found an old rectangular blanket. It turned out that the blanket is split in $$$n \cdot m$$$ colored pieces that form a rectangle with $$$n$$$ rows and $$$m$$$ columns. The colored pieces attracted Innokenty's attention so he immediately came up with the following business plan. If he cuts out a subrectangle consisting of three colored stripes, he can sell it as a flag of some country. Innokenty decided that a subrectangle is similar enough to a flag of some country if it consists of three stripes of equal heights placed one above another, where each stripe consists of cells of equal color. Of course, the color of the top stripe must be different from the color of the middle stripe; and the color of the middle stripe must be different from the color of the bottom stripe.Innokenty has not yet decided what part he will cut out, but he is sure that the flag's boundaries should go along grid lines. Also, Innokenty won't rotate the blanket. Please help Innokenty and count the number of different subrectangles Innokenty can cut out and sell as a flag. Two subrectangles located in different places but forming the same flag are still considered different. These subrectangles are flags. These subrectangles are not flags. | [] |
Bob came to a cash & carry store, put n items into his trolley, and went to the checkout counter to pay. Each item is described by its price ci and time ti in seconds that a checkout assistant spends on this item. While the checkout assistant is occupied with some item, Bob can steal some other items from his trolley. To steal one item Bob needs exactly 1 second. What is the minimum amount of money that Bob will have to pay to the checkout assistant? Remember, please, that it is Bob, who determines the order of items for the checkout assistant. | [] |
Recently an official statement of the world Olympic Committee said that the Olympic Winter Games 2030 will be held in Tomsk. The city officials decided to prepare for the Olympics thoroughly and to build all the necessary Olympic facilities as early as possible. First, a biathlon track will be built.To construct a biathlon track a plot of land was allocated, which is a rectangle divided into n × m identical squares. Each of the squares has two coordinates: the number of the row (from 1 to n), where it is located, the number of the column (from 1 to m), where it is located. Also each of the squares is characterized by its height. During the sports the biathletes will have to move from one square to another. If a biathlete moves from a higher square to a lower one, he makes a descent. If a biathlete moves from a lower square to a higher one, he makes an ascent. If a biathlete moves between two squares with the same height, then he moves on flat ground.The biathlon track should be a border of some rectangular area of the allocated land on which biathletes will move in the clockwise direction. It is known that on one move on flat ground an average biathlete spends tp seconds, an ascent takes tu seconds, a descent takes td seconds. The Tomsk Administration wants to choose the route so that the average biathlete passes it in as close to t seconds as possible. In other words, the difference between time ts of passing the selected track and t should be minimum.For a better understanding you can look at the first sample of the input data. In this sample n = 6, m = 7, and the administration wants the track covering time to be as close to t = 48 seconds as possible, also, tp = 3, tu = 6 and td = 2. If we consider the rectangle shown on the image by arrows, the average biathlete can move along the boundary in a clockwise direction in exactly 48 seconds. The upper left corner of this track is located in the square with the row number 4, column number 3 and the lower right corner is at square with row number 6, column number 7. Among other things the administration wants all sides of the rectangle which boundaries will be the biathlon track to consist of no less than three squares and to be completely contained within the selected land.You are given the description of the given plot of land and all necessary time values. You are to write the program to find the most suitable rectangle for a biathlon track. If there are several such rectangles, you are allowed to print any of them. | [] |
Piegirl is buying stickers for a project. Stickers come on sheets, and each sheet of stickers contains exactly n stickers. Each sticker has exactly one character printed on it, so a sheet of stickers can be described by a string of length n. Piegirl wants to create a string s using stickers. She may buy as many sheets of stickers as she wants, and may specify any string of length n for the sheets, but all the sheets must be identical, so the string is the same for all sheets. Once she attains the sheets of stickers, she will take some of the stickers from the sheets and arrange (in any order) them to form s. Determine the minimum number of sheets she has to buy, and provide a string describing a possible sheet of stickers she should buy. | [] |
The academic year has just begun, but lessons and olympiads have already occupied all the free time. It is not a surprise that today Olga fell asleep on the Literature. She had a dream in which she was on a stairs. The stairs consists of n steps. The steps are numbered from bottom to top, it means that the lowest step has number 1, and the highest step has number n. Above each of them there is a pointer with the direction (up or down) Olga should move from this step. As soon as Olga goes to the next step, the direction of the pointer (above the step she leaves) changes. It means that the direction "up" changes to "down", the direction "down" — to the direction "up".Olga always moves to the next step in the direction which is shown on the pointer above the step. If Olga moves beyond the stairs, she will fall and wake up. Moving beyond the stairs is a moving down from the first step or moving up from the last one (it means the n-th) step. In one second Olga moves one step up or down according to the direction of the pointer which is located above the step on which Olga had been at the beginning of the second. For each step find the duration of the dream if Olga was at this step at the beginning of the dream.Olga's fall also takes one second, so if she was on the first step and went down, she would wake up in the next second. | ['math'] |
While walking down the street Vanya saw a label "Hide&Seek". Because he is a programmer, he used & as a bitwise AND for these two words represented as a integers in base 64 and got new word. Now Vanya thinks of some string s and wants to know the number of pairs of words of length |s| (length of s), such that their bitwise AND is equal to s. As this number can be large, output it modulo 109 + 7.To represent the string as a number in numeral system with base 64 Vanya uses the following rules: digits from '0' to '9' correspond to integers from 0 to 9; letters from 'A' to 'Z' correspond to integers from 10 to 35; letters from 'a' to 'z' correspond to integers from 36 to 61; letter '-' correspond to integer 62; letter '_' correspond to integer 63. | ['strings'] |
Arkady and Masha want to choose decorations for thier aquarium in Fishdom game. They have n decorations to choose from, each of them has some cost. To complete a task Arkady and Masha need to choose exactly m decorations from given, and they want to spend as little money as possible.There is one difficulty: Masha likes some a of the given decorations, Arkady likes some b of the given decorations. Some decorations may be liked by both Arkady and Masha, or not be liked by both. The friends want to choose such decorations so that each of them likes at least k decorations among the chosen. Help Masha and Arkady find the minimum sum of money they need to spend. | [] |
There are $$$n$$$ players sitting at the card table. Each player has a favorite number. The favorite number of the $$$j$$$-th player is $$$f_j$$$.There are $$$k \cdot n$$$ cards on the table. Each card contains a single integer: the $$$i$$$-th card contains number $$$c_i$$$. Also, you are given a sequence $$$h_1, h_2, \dots, h_k$$$. Its meaning will be explained below.The players have to distribute all the cards in such a way that each of them will hold exactly $$$k$$$ cards. After all the cards are distributed, each player counts the number of cards he has that contains his favorite number. The joy level of a player equals $$$h_t$$$ if the player holds $$$t$$$ cards containing his favorite number. If a player gets no cards with his favorite number (i.e., $$$t=0$$$), his joy level is $$$0$$$.Print the maximum possible total joy levels of the players after the cards are distributed. Note that the sequence $$$h_1, \dots, h_k$$$ is the same for all the players. | [] |
There are $$$n$$$ points on a plane. The $$$i$$$-th point has coordinates $$$(x_i, y_i)$$$. You have two horizontal platforms, both of length $$$k$$$. Each platform can be placed anywhere on a plane but it should be placed horizontally (on the same $$$y$$$-coordinate) and have integer borders. If the left border of the platform is $$$(x, y)$$$ then the right border is $$$(x + k, y)$$$ and all points between borders (including borders) belong to the platform.Note that platforms can share common points (overlap) and it is not necessary to place both platforms on the same $$$y$$$-coordinate.When you place both platforms on a plane, all points start falling down decreasing their $$$y$$$-coordinate. If a point collides with some platform at some moment, the point stops and is saved. Points which never collide with any platform are lost.Your task is to find the maximum number of points you can save if you place both platforms optimally.You have to answer $$$t$$$ independent test cases.For better understanding, please read the Note section below to see a picture for the first test case. | [] |
During the break, we decided to relax and play dominoes. Our box with Domino was empty, so we decided to borrow the teacher's dominoes.The teacher responded instantly at our request. He put nm dominoes on the table as an n × 2m rectangle so that each of the n rows contained m dominoes arranged horizontally. Each half of each domino contained number (0 or 1).We were taken aback, and the teacher smiled and said: "Consider some arrangement of dominoes in an n × 2m matrix. Let's count for each column of the matrix the sum of numbers in this column. Then among all such sums find the maximum one. Can you rearrange the dominoes in the matrix in such a way that the maximum sum will be minimum possible? Note that it is prohibited to change the orientation of the dominoes, they all need to stay horizontal, nevertheless dominoes are allowed to rotate by 180 degrees. As a reward I will give you all my dominoes".We got even more taken aback. And while we are wondering what was going on, help us make an optimal matrix of dominoes. | [] |
School holidays come in Berland. The holidays are going to continue for n days. The students of school №N are having the time of their lives and the IT teacher Marina Sergeyevna, who has spent all the summer busy checking the BSE (Berland State Examination) results, has finally taken a vacation break! Some people are in charge of the daily watering of flowers in shifts according to the schedule. However when Marina Sergeyevna was making the schedule, she was so tired from work and so lost in dreams of the oncoming vacation that she perhaps made several mistakes. In fact, it is possible that according to the schedule, on some days during the holidays the flowers will not be watered or will be watered multiple times. Help Marina Sergeyevna to find a mistake. | [] |
Alice has a very important message M consisting of some non-negative integers that she wants to keep secret from Eve. Alice knows that the only theoretically secure cipher is one-time pad. Alice generates a random key K of the length equal to the message's length. Alice computes the bitwise xor of each element of the message and the key (, where denotes the bitwise XOR operation) and stores this encrypted message A. Alice is smart. Be like Alice.For example, Alice may have wanted to store a message M = (0, 15, 9, 18). She generated a key K = (16, 7, 6, 3). The encrypted message is thus A = (16, 8, 15, 17).Alice realised that she cannot store the key with the encrypted message. Alice sent her key K to Bob and deleted her own copy. Alice is smart. Really, be like Alice.Bob realised that the encrypted message is only secure as long as the key is secret. Bob thus randomly permuted the key before storing it. Bob thinks that this way, even if Eve gets both the encrypted message and the key, she will not be able to read the message. Bob is not smart. Don't be like Bob.In the above example, Bob may have, for instance, selected a permutation (3, 4, 1, 2) and stored the permuted key P = (6, 3, 16, 7).One year has passed and Alice wants to decrypt her message. Only now Bob has realised that this is impossible. As he has permuted the key randomly, the message is lost forever. Did we mention that Bob isn't smart?Bob wants to salvage at least some information from the message. Since he is not so smart, he asks for your help. You know the encrypted message A and the permuted key P. What is the lexicographically smallest message that could have resulted in the given encrypted text?More precisely, for given A and P, find the lexicographically smallest message O, for which there exists a permutation π such that for every i.Note that the sequence S is lexicographically smaller than the sequence T, if there is an index i such that Si < Ti and for all j < i the condition Sj = Tj holds. | ['strings', 'trees'] |
This is the hard version of the problem. The only difference between the easy version and the hard version is the constraints on $$$n$$$. You can only make hacks if both versions are solved.A permutation of $$$1, 2, \ldots, n$$$ is a sequence of $$$n$$$ integers, where each integer from $$$1$$$ to $$$n$$$ appears exactly once. For example, $$$[2,3,1,4]$$$ is a permutation of $$$1, 2, 3, 4$$$, but $$$[1,4,2,2]$$$ isn't because $$$2$$$ appears twice in it.Recall that the number of inversions in a permutation $$$a_1, a_2, \ldots, a_n$$$ is the number of pairs of indices $$$(i, j)$$$ such that $$$i < j$$$ and $$$a_i > a_j$$$.Let $$$p$$$ and $$$q$$$ be two permutations of $$$1, 2, \ldots, n$$$. Find the number of permutation pairs $$$(p,q)$$$ that satisfy the following conditions: $$$p$$$ is lexicographically smaller than $$$q$$$. the number of inversions in $$$p$$$ is greater than the number of inversions in $$$q$$$. Print the number of such pairs modulo $$$mod$$$. Note that $$$mod$$$ may not be a prime. | ['math'] |
There are $$$n$$$ cities numbered from $$$1$$$ to $$$n$$$, and city $$$i$$$ has beauty $$$a_i$$$.A salesman wants to start at city $$$1$$$, visit every city exactly once, and return to city $$$1$$$.For all $$$i\ne j$$$, a flight from city $$$i$$$ to city $$$j$$$ costs $$$\max(c_i,a_j-a_i)$$$ dollars, where $$$c_i$$$ is the price floor enforced by city $$$i$$$. Note that there is no absolute value. Find the minimum total cost for the salesman to complete his trip. | ['graphs'] |
A known chef has prepared $$$n$$$ dishes: the $$$i$$$-th dish consists of $$$a_i$$$ grams of fish and $$$b_i$$$ grams of meat. The banquet organizers estimate the balance of $$$n$$$ dishes as follows. The balance is equal to the absolute value of the difference between the total mass of fish and the total mass of meat.Technically, the balance equals to $$$\left|\sum\limits_{i=1}^n a_i - \sum\limits_{i=1}^n b_i\right|$$$. The smaller the balance, the better.In order to improve the balance, a taster was invited. He will eat exactly $$$m$$$ grams of food from each dish. For each dish, the taster determines separately how much fish and how much meat he will eat. The only condition is that he should eat exactly $$$m$$$ grams of each dish in total.Determine how much of what type of food the taster should eat from each dish so that the value of the balance is as minimal as possible. If there are several correct answers, you may choose any of them. | [] |
This is the hard version of this problem. In this version, we have queries. Note that we do not have multiple test cases in this version. You can make hacks only if both versions of the problem are solved.An array $$$b$$$ of length $$$m$$$ is good if for all $$$i$$$ the $$$i$$$-th element is greater than or equal to $$$i$$$. In other words, $$$b$$$ is good if and only if $$$b_i \geq i$$$ for all $$$i$$$ ($$$1 \leq i \leq m$$$).You are given an array $$$a$$$ consisting of $$$n$$$ positive integers, and you are asked $$$q$$$ queries. In each query, you are given two integers $$$p$$$ and $$$x$$$ ($$$1 \leq p,x \leq n$$$). You have to do $$$a_p := x$$$ (assign $$$x$$$ to $$$a_p$$$). In the updated array, find the number of pairs of indices $$$(l, r)$$$, where $$$1 \le l \le r \le n$$$, such that the array $$$[a_l, a_{l+1}, \ldots, a_r]$$$ is good.Note that all queries are independent, which means after each query, the initial array $$$a$$$ is restored. | [] |
Moamen has an array of $$$n$$$ distinct integers. He wants to sort that array in non-decreasing order by doing the following operations in order exactly once: Split the array into exactly $$$k$$$ non-empty subarrays such that each element belongs to exactly one subarray. Reorder these subarrays arbitrary. Merge the subarrays in their new order. A sequence $$$a$$$ is a subarray of a sequence $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end.Can you tell Moamen if there is a way to sort the array in non-decreasing order using the operations written above? | [] |
Kuro has just learned about permutations and he is really excited to create a new permutation type. He has chosen $$$n$$$ distinct positive integers and put all of them in a set $$$S$$$. Now he defines a magical permutation to be: A permutation of integers from $$$0$$$ to $$$2^x - 1$$$, where $$$x$$$ is a non-negative integer. The bitwise xor of any two consecutive elements in the permutation is an element in $$$S$$$.Since Kuro is really excited about magical permutations, he wants to create the longest magical permutation possible. In other words, he wants to find the largest non-negative integer $$$x$$$ such that there is a magical permutation of integers from $$$0$$$ to $$$2^x - 1$$$. Since he is a newbie in the subject, he wants you to help him find this value of $$$x$$$ and also the magical permutation for that $$$x$$$. | ['math', 'graphs'] |
Andrew was very excited to participate in Olympiad of Metropolises. Days flew by quickly, and Andrew is already at the airport, ready to go home. He has $$$n$$$ rubles left, and would like to exchange them to euro and dollar bills. Andrew can mix dollar bills and euro bills in whatever way he wants. The price of one dollar is $$$d$$$ rubles, and one euro costs $$$e$$$ rubles.Recall that there exist the following dollar bills: $$$1$$$, $$$2$$$, $$$5$$$, $$$10$$$, $$$20$$$, $$$50$$$, $$$100$$$, and the following euro bills — $$$5$$$, $$$10$$$, $$$20$$$, $$$50$$$, $$$100$$$, $$$200$$$ (note that, in this problem we do not consider the $$$500$$$ euro bill, it is hard to find such bills in the currency exchange points). Andrew can buy any combination of bills, and his goal is to minimize the total number of rubles he will have after the exchange.Help him — write a program that given integers $$$n$$$, $$$e$$$ and $$$d$$$, finds the minimum number of rubles Andrew can get after buying dollar and euro bills. | ['math'] |
The map of Bertown can be represented as a set of $$$n$$$ intersections, numbered from $$$1$$$ to $$$n$$$ and connected by $$$m$$$ one-way roads. It is possible to move along the roads from any intersection to any other intersection. The length of some path from one intersection to another is the number of roads that one has to traverse along the path. The shortest path from one intersection $$$v$$$ to another intersection $$$u$$$ is the path that starts in $$$v$$$, ends in $$$u$$$ and has the minimum length among all such paths.Polycarp lives near the intersection $$$s$$$ and works in a building near the intersection $$$t$$$. Every day he gets from $$$s$$$ to $$$t$$$ by car. Today he has chosen the following path to his workplace: $$$p_1$$$, $$$p_2$$$, ..., $$$p_k$$$, where $$$p_1 = s$$$, $$$p_k = t$$$, and all other elements of this sequence are the intermediate intersections, listed in the order Polycarp arrived at them. Polycarp never arrived at the same intersection twice, so all elements of this sequence are pairwise distinct. Note that you know Polycarp's path beforehand (it is fixed), and it is not necessarily one of the shortest paths from $$$s$$$ to $$$t$$$.Polycarp's car has a complex navigation system installed in it. Let's describe how it works. When Polycarp starts his journey at the intersection $$$s$$$, the system chooses some shortest path from $$$s$$$ to $$$t$$$ and shows it to Polycarp. Let's denote the next intersection in the chosen path as $$$v$$$. If Polycarp chooses to drive along the road from $$$s$$$ to $$$v$$$, then the navigator shows him the same shortest path (obviously, starting from $$$v$$$ as soon as he arrives at this intersection). However, if Polycarp chooses to drive to another intersection $$$w$$$ instead, the navigator rebuilds the path: as soon as Polycarp arrives at $$$w$$$, the navigation system chooses some shortest path from $$$w$$$ to $$$t$$$ and shows it to Polycarp. The same process continues until Polycarp arrives at $$$t$$$: if Polycarp moves along the road recommended by the system, it maintains the shortest path it has already built; but if Polycarp chooses some other path, the system rebuilds the path by the same rules.Here is an example. Suppose the map of Bertown looks as follows, and Polycarp drives along the path $$$[1, 2, 3, 4]$$$ ($$$s = 1$$$, $$$t = 4$$$): Check the picture by the link http://tk.codeforces.com/a.png When Polycarp starts at $$$1$$$, the system chooses some shortest path from $$$1$$$ to $$$4$$$. There is only one such path, it is $$$[1, 5, 4]$$$; Polycarp chooses to drive to $$$2$$$, which is not along the path chosen by the system. When Polycarp arrives at $$$2$$$, the navigator rebuilds the path by choosing some shortest path from $$$2$$$ to $$$4$$$, for example, $$$[2, 6, 4]$$$ (note that it could choose $$$[2, 3, 4]$$$); Polycarp chooses to drive to $$$3$$$, which is not along the path chosen by the system. When Polycarp arrives at $$$3$$$, the navigator rebuilds the path by choosing the only shortest path from $$$3$$$ to $$$4$$$, which is $$$[3, 4]$$$; Polycarp arrives at $$$4$$$ along the road chosen by the navigator, so the system does not have to rebuild anything. Overall, we get $$$2$$$ rebuilds in this scenario. Note that if the system chose $$$[2, 3, 4]$$$ instead of $$$[2, 6, 4]$$$ during the second step, there would be only $$$1$$$ rebuild (since Polycarp goes along the path, so the system maintains the path $$$[3, 4]$$$ during the third step).The example shows us that the number of rebuilds can differ even if the map of Bertown and the path chosen by Polycarp stays the same. Given this information (the map and Polycarp's path), can you determine the minimum and the maximum number of rebuilds that could have happened during the journey? | ['graphs'] |
You are given an integer $$$n$$$. In $$$1$$$ move, you can do one of the following actions: erase any digit of the number (it's acceptable that the number before the operation has exactly one digit and after the operation, it is "empty"); add one digit to the right. The actions may be performed in any order any number of times.Note that if, after deleting some digit from a number, it will contain leading zeroes, they will not be deleted. E.g. if you delete from the number $$$301$$$ the digit $$$3$$$, the result is the number $$$01$$$ (not $$$1$$$).You need to perform the minimum number of actions to make the number any power of $$$2$$$ (i.e. there's an integer $$$k$$$ ($$$k \ge 0$$$) such that the resulting number is equal to $$$2^k$$$). The resulting number must not have leading zeroes.E.g. consider $$$n=1052$$$. The answer is equal to $$$2$$$. First, let's add to the right one digit $$$4$$$ (the result will be $$$10524$$$). Then let's erase the digit $$$5$$$, so the result will be $$$1024$$$ which is a power of $$$2$$$.E.g. consider $$$n=8888$$$. The answer is equal to $$$3$$$. Let's erase any of the digits $$$8$$$ three times. The result will be $$$8$$$ which is a power of $$$2$$$. | ['math', 'strings'] |
Sonya was unable to think of a story for this problem, so here comes the formal description.You are given the array containing n positive integers. At one turn you can pick any element and increase or decrease it by 1. The goal is the make the array strictly increasing by making the minimum possible number of operations. You are allowed to change elements in any way, they can become negative or equal to 0. | [] |
A programming coach has n students to teach. We know that n is divisible by 3. Let's assume that all students are numbered from 1 to n, inclusive.Before the university programming championship the coach wants to split all students into groups of three. For some pairs of students we know that they want to be on the same team. Besides, if the i-th student wants to be on the same team with the j-th one, then the j-th student wants to be on the same team with the i-th one. The coach wants the teams to show good results, so he wants the following condition to hold: if the i-th student wants to be on the same team with the j-th, then the i-th and the j-th students must be on the same team. Also, it is obvious that each student must be on exactly one team.Help the coach and divide the teams the way he wants. | ['graphs'] |
You are given sequence a1, a2, ..., an of integer numbers of length n. Your task is to find such subsequence that its sum is odd and maximum among all such subsequences. It's guaranteed that given sequence contains subsequence with odd sum.Subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.You should write a program which finds sum of the best subsequence. | [] |
You are given a tree (an undirected connected acyclic graph) consisting of $$$n$$$ vertices. You are playing a game on this tree.Initially all vertices are white. On the first turn of the game you choose one vertex and paint it black. Then on each turn you choose a white vertex adjacent (connected by an edge) to any black vertex and paint it black.Each time when you choose a vertex (even during the first turn), you gain the number of points equal to the size of the connected component consisting only of white vertices that contains the chosen vertex. The game ends when all vertices are painted black.Let's see the following example:Vertices $$$1$$$ and $$$4$$$ are painted black already. If you choose the vertex $$$2$$$, you will gain $$$4$$$ points for the connected component consisting of vertices $$$2, 3, 5$$$ and $$$6$$$. If you choose the vertex $$$9$$$, you will gain $$$3$$$ points for the connected component consisting of vertices $$$7, 8$$$ and $$$9$$$.Your task is to maximize the number of points you gain. | ['trees'] |
Polycarp has an array $$$a$$$ consisting of $$$n$$$ integers.He wants to play a game with this array. The game consists of several moves. On the first move he chooses any element and deletes it (after the first move the array contains $$$n-1$$$ elements). For each of the next moves he chooses any element with the only restriction: its parity should differ from the parity of the element deleted on the previous move. In other words, he alternates parities (even-odd-even-odd-... or odd-even-odd-even-...) of the removed elements. Polycarp stops if he can't make a move.Formally: If it is the first move, he chooses any element and deletes it; If it is the second or any next move: if the last deleted element was odd, Polycarp chooses any even element and deletes it; if the last deleted element was even, Polycarp chooses any odd element and deletes it. If after some move Polycarp cannot make a move, the game ends. Polycarp's goal is to minimize the sum of non-deleted elements of the array after end of the game. If Polycarp can delete the whole array, then the sum of non-deleted elements is zero.Help Polycarp find this value. | [] |
You are given two strings of equal length $$$s$$$ and $$$t$$$ consisting of lowercase Latin letters. You may perform any number (possibly, zero) operations on these strings.During each operation you choose two adjacent characters in any string and assign the value of the first character to the value of the second or vice versa.For example, if $$$s$$$ is "acbc" you can get the following strings in one operation: "aabc" (if you perform $$$s_2 = s_1$$$); "ccbc" (if you perform $$$s_1 = s_2$$$); "accc" (if you perform $$$s_3 = s_2$$$ or $$$s_3 = s_4$$$); "abbc" (if you perform $$$s_2 = s_3$$$); "acbb" (if you perform $$$s_4 = s_3$$$); Note that you can also apply this operation to the string $$$t$$$.Please determine whether it is possible to transform $$$s$$$ into $$$t$$$, applying the operation above any number of times.Note that you have to answer $$$q$$$ independent queries. | ['strings'] |
Let's denote that some array $$$b$$$ is bad if it contains a subarray $$$b_l, b_{l+1}, \dots, b_{r}$$$ of odd length more than $$$1$$$ ($$$l < r$$$ and $$$r - l + 1$$$ is odd) such that $$$\forall i \in \{0, 1, \dots, r - l\}$$$ $$$b_{l + i} = b_{r - i}$$$.If an array is not bad, it is good.Now you are given an array $$$a_1, a_2, \dots, a_n$$$. Some elements are replaced by $$$-1$$$. Calculate the number of good arrays you can obtain by replacing each $$$-1$$$ with some integer from $$$1$$$ to $$$k$$$.Since the answer can be large, print it modulo $$$998244353$$$. | [] |
Monocarp is playing a computer game. Now he wants to complete the first level of this game.A level is a rectangular grid of $$$2$$$ rows and $$$n$$$ columns. Monocarp controls a character, which starts in cell $$$(1, 1)$$$ — at the intersection of the $$$1$$$-st row and the $$$1$$$-st column.Monocarp's character can move from one cell to another in one step if the cells are adjacent by side and/or corner. Formally, it is possible to move from cell $$$(x_1, y_1)$$$ to cell $$$(x_2, y_2)$$$ in one step if $$$|x_1 - x_2| \le 1$$$ and $$$|y_1 - y_2| \le 1$$$. Obviously, it is prohibited to go outside the grid.There are traps in some cells. If Monocarp's character finds himself in such a cell, he dies, and the game ends.To complete a level, Monocarp's character should reach cell $$$(2, n)$$$ — at the intersection of row $$$2$$$ and column $$$n$$$.Help Monocarp determine if it is possible to complete the level. | [] |
This is an interactive problem.A legendary tree rests deep in the forest. Legend has it that individuals who realize this tree would eternally become a Legendary Grandmaster.To help you determine the tree, Mikaela the Goddess has revealed to you that the tree contains $$$n$$$ vertices, enumerated from $$$1$$$ through $$$n$$$. She also allows you to ask her some questions as follows. For each question, you should tell Mikaela some two disjoint non-empty sets of vertices $$$S$$$ and $$$T$$$, along with any vertex $$$v$$$ that you like. Then, Mikaela will count and give you the number of pairs of vertices $$$(s, t)$$$ where $$$s \in S$$$ and $$$t \in T$$$ such that the simple path from $$$s$$$ to $$$t$$$ contains $$$v$$$.Mikaela the Goddess is busy and will be available to answer at most $$$11\,111$$$ questions.This is your only chance. Your task is to determine the tree and report its edges. | ['trees'] |
Let's call a string "s-palindrome" if it is symmetric about the middle of the string. For example, the string "oHo" is "s-palindrome", but the string "aa" is not. The string "aa" is not "s-palindrome", because the second half of it is not a mirror reflection of the first half. English alphabet You are given a string s. Check if the string is "s-palindrome". | ['strings'] |
Recently Ivan noticed an array a while debugging his code. Now Ivan can't remember this array, but the bug he was trying to fix didn't go away, so Ivan thinks that the data from this array might help him to reproduce the bug.Ivan clearly remembers that there were n elements in the array, and each element was not less than 1 and not greater than n. Also he remembers q facts about the array. There are two types of facts that Ivan remembers: 1 li ri vi — for each x such that li ≤ x ≤ ri ax ≥ vi; 2 li ri vi — for each x such that li ≤ x ≤ ri ax ≤ vi. Also Ivan thinks that this array was a permutation, but he is not so sure about it. He wants to restore some array that corresponds to the q facts that he remembers and is very similar to permutation. Formally, Ivan has denoted the cost of array as follows:, where cnt(i) is the number of occurences of i in the array.Help Ivan to determine minimum possible cost of the array that corresponds to the facts! | [] |
Mocha is a young girl from high school. She has learned so much interesting knowledge from her teachers, especially her math teacher. Recently, Mocha is learning about binary system and very interested in bitwise operation.This day, Mocha got a sequence $$$a$$$ of length $$$n$$$. In each operation, she can select an arbitrary interval $$$[l, r]$$$ and for all values $$$i$$$ ($$$0\leq i \leq r-l$$$), replace $$$a_{l+i}$$$ with $$$a_{l+i} \,\&\, a_{r-i}$$$ at the same time, where $$$\&$$$ denotes the bitwise AND operation. This operation can be performed any number of times.For example, if $$$n=5$$$, the array is $$$[a_1,a_2,a_3,a_4,a_5]$$$, and Mocha selects the interval $$$[2,5]$$$, then the new array is $$$[a_1,a_2\,\&\, a_5, a_3\,\&\, a_4, a_4\,\&\, a_3, a_5\,\&\, a_2]$$$.Now Mocha wants to minimize the maximum value in the sequence. As her best friend, can you help her to get the answer? | ['math'] |
To celebrate the second ABBYY Cup tournament, the Smart Beaver decided to throw a party. The Beaver has a lot of acquaintances, some of them are friends with each other, and some of them dislike each other. To make party successful, the Smart Beaver wants to invite only those of his friends who are connected by friendship relations, and not to invite those who dislike each other. Both friendship and dislike are mutual feelings.More formally, for each invited person the following conditions should be fulfilled: all his friends should also be invited to the party; the party shouldn't have any people he dislikes; all people who are invited to the party should be connected with him by friendship either directly or through a chain of common friends of arbitrary length. We'll say that people a1 and ap are connected through a chain of common friends if there exists a sequence of people a2, a3, ..., ap - 1 such that all pairs of people ai and ai + 1 (1 ≤ i < p) are friends. Help the Beaver find the maximum number of acquaintances he can invite. | ['graphs'] |
Arkady is playing Battleship. The rules of this game aren't really important.There is a field of $$$n \times n$$$ cells. There should be exactly one $$$k$$$-decker on the field, i. e. a ship that is $$$k$$$ cells long oriented either horizontally or vertically. However, Arkady doesn't know where it is located. For each cell Arkady knows if it is definitely empty or can contain a part of the ship.Consider all possible locations of the ship. Find such a cell that belongs to the maximum possible number of different locations of the ship. | [] |
By 2312 there were n Large Hadron Colliders in the inhabited part of the universe. Each of them corresponded to a single natural number from 1 to n. However, scientists did not know what activating several colliders simultaneously could cause, so the colliders were deactivated.In 2312 there was a startling discovery: a collider's activity is safe if and only if all numbers of activated colliders are pairwise relatively prime to each other (two numbers are relatively prime if their greatest common divisor equals 1)! If two colliders with relatively nonprime numbers are activated, it will cause a global collapse.Upon learning this, physicists rushed to turn the colliders on and off and carry out all sorts of experiments. To make sure than the scientists' quickness doesn't end with big trouble, the Large Hadron Colliders' Large Remote Control was created. You are commissioned to write the software for the remote (well, you do not expect anybody to operate it manually, do you?).Initially, all colliders are deactivated. Your program receives multiple requests of the form "activate/deactivate the i-th collider". The program should handle requests in the order of receiving them. The program should print the processed results in the format described below.To the request of "+ i" (that is, to activate the i-th collider), the program should print exactly one of the following responses: "Success" if the activation was successful. "Already on", if the i-th collider was already activated before the request. "Conflict with j", if there is a conflict with the j-th collider (that is, the j-th collider is on, and numbers i and j are not relatively prime). In this case, the i-th collider shouldn't be activated. If a conflict occurs with several colliders simultaneously, you should print the number of any of them. The request of "- i" (that is, to deactivate the i-th collider), should receive one of the following responses from the program: "Success", if the deactivation was successful. "Already off", if the i-th collider was already deactivated before the request. You don't need to print quotes in the output of the responses to the requests. | ['math', 'number theory'] |
Lee is used to finish his stories in a stylish way, this time he barely failed it, but Ice Bear came and helped him. Lee is so grateful for it, so he decided to show Ice Bear his new game called "Critic"...The game is a one versus one game. It has $$$t$$$ rounds, each round has two integers $$$s_i$$$ and $$$e_i$$$ (which are determined and are known before the game begins, $$$s_i$$$ and $$$e_i$$$ may differ from round to round). The integer $$$s_i$$$ is written on the board at the beginning of the corresponding round. The players will take turns. Each player will erase the number on the board (let's say it was $$$a$$$) and will choose to write either $$$2 \cdot a$$$ or $$$a + 1$$$ instead. Whoever writes a number strictly greater than $$$e_i$$$ loses that round and the other one wins that round.Now Lee wants to play "Critic" against Ice Bear, for each round he has chosen the round's $$$s_i$$$ and $$$e_i$$$ in advance. Lee will start the first round, the loser of each round will start the next round.The winner of the last round is the winner of the game, and the loser of the last round is the loser of the game.Determine if Lee can be the winner independent of Ice Bear's moves or not. Also, determine if Lee can be the loser independent of Ice Bear's moves or not. | ['games'] |
There are $$$n$$$ logs, the $$$i$$$-th log has a length of $$$a_i$$$ meters. Since chopping logs is tiring work, errorgorn and maomao90 have decided to play a game.errorgorn and maomao90 will take turns chopping the logs with errorgorn chopping first. On his turn, the player will pick a log and chop it into $$$2$$$ pieces. If the length of the chosen log is $$$x$$$, and the lengths of the resulting pieces are $$$y$$$ and $$$z$$$, then $$$y$$$ and $$$z$$$ have to be positive integers, and $$$x=y+z$$$ must hold. For example, you can chop a log of length $$$3$$$ into logs of lengths $$$2$$$ and $$$1$$$, but not into logs of lengths $$$3$$$ and $$$0$$$, $$$2$$$ and $$$2$$$, or $$$1.5$$$ and $$$1.5$$$.The player who is unable to make a chop will be the loser. Assuming that both errorgorn and maomao90 play optimally, who will be the winner? | ['math', 'games'] |
Vasya is a CEO of a big construction company. And as any other big boss he has a spacious, richly furnished office with two crystal chandeliers. To stay motivated Vasya needs the color of light at his office to change every day. That's why he ordered both chandeliers that can change its color cyclically. For example: red – brown – yellow – red – brown – yellow and so on. There are many chandeliers that differs in color set or order of colors. And the person responsible for the light made a critical mistake — they bought two different chandeliers.Since chandeliers are different, some days they will have the same color, but some days — different. Of course, it looks poor and only annoys Vasya. As a result, at the $$$k$$$-th time when chandeliers will light with different colors, Vasya will become very angry and, most probably, will fire the person who bought chandeliers.Your task is to calculate the day, when it happens (counting from the day chandeliers were installed). You can think that Vasya works every day without weekends and days off. | ['math', 'number theory'] |
Ehab loves number theory, but for some reason he hates the number $$$x$$$. Given an array $$$a$$$, find the length of its longest subarray such that the sum of its elements isn't divisible by $$$x$$$, or determine that such subarray doesn't exist.An array $$$a$$$ is a subarray of an array $$$b$$$ if $$$a$$$ can be obtained from $$$b$$$ by deletion of several (possibly, zero or all) elements from the beginning and several (possibly, zero or all) elements from the end. | ['number theory'] |
Valera runs a 24/7 fast food cafe. He magically learned that next day n people will visit his cafe. For each person we know the arrival time: the i-th person comes exactly at hi hours mi minutes. The cafe spends less than a minute to serve each client, but if a client comes in and sees that there is no free cash, than he doesn't want to wait and leaves the cafe immediately. Valera is very greedy, so he wants to serve all n customers next day (and get more profit). However, for that he needs to ensure that at each moment of time the number of working cashes is no less than the number of clients in the cafe. Help Valera count the minimum number of cashes to work at his cafe next day, so that they can serve all visitors. | [] |
Nian is a monster which lives deep in the oceans. Once a year, it shows up on the land, devouring livestock and even people. In order to keep the monster away, people fill their villages with red colour, light, and cracking noise, all of which frighten the monster out of coming.Little Tommy has n lanterns and Big Banban has m lanterns. Tommy's lanterns have brightness a1, a2, ..., an, and Banban's have brightness b1, b2, ..., bm respectively.Tommy intends to hide one of his lanterns, then Banban picks one of Tommy's non-hidden lanterns and one of his own lanterns to form a pair. The pair's brightness will be the product of the brightness of two lanterns.Tommy wants to make the product as small as possible, while Banban tries to make it as large as possible.You are asked to find the brightness of the chosen pair if both of them choose optimally. | ['games'] |
A company has n employees numbered from 1 to n. Each employee either has no immediate manager or exactly one immediate manager, who is another employee with a different number. An employee A is said to be the superior of another employee B if at least one of the following is true: Employee A is the immediate manager of employee B Employee B has an immediate manager employee C such that employee A is the superior of employee C. The company will not have a managerial cycle. That is, there will not exist an employee who is the superior of his/her own immediate manager.Today the company is going to arrange a party. This involves dividing all n employees into several groups: every employee must belong to exactly one group. Furthermore, within any single group, there must not be two employees A and B such that A is the superior of B.What is the minimum number of groups that must be formed? | ['graphs', 'trees'] |
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