Zonal Computing Olympiad 2012, 26 Nov 2011

We consider sequences of opening and closing brackets with two types of brackets, () and [].  A bracket sequence is well-bracketed if we can pair up each opening bracket with a matching closing bracket in the usual sense.  For instance, the sequences (), [] ([]) and []([]) are well-bracketed, while (, ()], (], )( and [(]) are not well-bracketed.  In the last case, each opening bracket has a matching closing bracket and vice versa, but the intervals spanned by the different types of brackets intersect each other instead of being contained one within the other.

The alternating depth of a well-bracketed sequence tells us the maximum number of times we switch between the two types of brackets when we have inner matched brackets enclosed within outer matched brackets.  For instance, the alternating depth of (), [[[]]] and ()[][] is 1, the alternating depth of [()] and ()([]) is 2, the alternating depth of ([()]) and [()][(([]))] is 3, and so on.

Given a well-bracketed sequence, we are interested in computing three quantities.
- The alternating depth of the sequence.
- The maximum number of symbols between any pair of matched brackets of the type ( and ), including both the outer brackets.
- The maximum number of symbols between any pair of matched brackets of the type [ and ], including both the outer brackets.

For instance, the alternating depth of (([]))[[[()]]] is 2, the maximum number of symbols between a matched pair () is 6 and the maximum number of symbols between a matched pair [] is 8.



-----Input format-----
The input consists of two lines.  The first line is a single integer N, the length of the bracket sequence. Positions in the sequence are numbered 1,2,…,N. The second line is a sequence of N space-separated integers that encode the bracket expression as follows: 1 denotes an opening bracket (, 2 denotes a closing bracket ), 3 denotes an opening bracket [ and 4 denotes a closing bracket ].  Nothing other than 1, 2, 3 or 4 appears in the second line of input and the corresponding expression is guaranteed to be well-bracketed.

-----Output format-----
Your program should print 3 space-separated integers in a line, denoting the three quantities asked for in the following order: alternating depth, length of the maximum sequence between matching () brackets and length of the maximum sequence between matching [] brackets.  

-----Testdata-----
You may assume that 2 ≤ N ≤ 105.  In 30% of the test cases, 2 ≤ N ≤ 103.

- Subtask 1 (30 marks)
- Subtask 2 (70 marks)

-----Sample Input-----
14
1 1 3 4 2 2 3 3 3 1 2 4 4 4

-----Sample Output-----
2 6 8

Difficulty: UNKNOWN_DIFFICULTY

Starter code:

Solutions:
n = int(input())
stringa = list(map(int, input().split()))
counter = 0
counter1 = 0
counter3 = 0
somma1 = 0
somma2 = 0
massimo = 0
massimo1 = 0
massimo3 = 0
stack = []
for par in stringa:
	if par == 1 or par == 3:
		if counter1 == 0 and par == 1:
			counter1 = 1
			somma1 = 1
			massimo1 = max(massimo1, 1)
		elif counter1 > 0:
			counter1 += 1
			somma1 += 1
			massimo1 = max(massimo1, somma1)
		if counter3 == 0 and par == 3:
			counter3 = 1
			somma3 = 1
			massimo3 = max(massimo3, 1)
		elif counter3 > 0:
			counter3 += 1
			somma3 += 1
			massimo3 = max(massimo3, somma3)
		if counter == 0:
			counter = 1
			massimo = max(massimo, 1)
		if len(stack) > 0 and par != stack[-1]:
			counter += 1
			massimo = max(massimo, counter)
		stack.append(par)
	else:
		if counter1 > 0:
			counter1 -= 1
			somma1 += 1
			massimo1 = max(massimo1, somma1)
		if counter3 > 0:
			counter3 -= 1
			somma3 += 1
			massimo3 = max(massimo3, somma3)
		appo = stack.pop()
		if len(stack) > 0 and appo == stack[-1]:
			pass
		else:
			counter -= 1
print(massimo, massimo1, massimo3)


class Stack:

	def __init__(self):
		self.items = []

	def empty(self):
		return self.items == []

	def push(self, item):
		self.items.append(item)

	def pop(self):
		return self.items.pop()

	def top(self):
		return self.items[-1]

	def size(self):
		return len(self.items)

	def __iter__(self):
		return self

	def __next__(self):
		return _StackIterator(self.items())

class _StackIterator:

	def __init__(self, stack):
		self.stackRef = stack
		self.curInd = 0

	def __iter__(self):
		return self

	def __next__(self):
		if self.curInd < self.size():
			entry = self.stackRef[self.curInd]
			self.curInd += 1
			return entry
		else:
			raise StopIteration

def main():
	n = int(input())
	Symbol = Stack()
	Index = Stack()
	FirstBracket = ThirdBracket = 0
	arr = list(map(int, input().split()))
	for i in range(n):
		if arr[i] == 1 or arr[i] == 3:
			Symbol.push(arr[i])
			Index.push(i)
		else:
			temp = Symbol.pop()
			if temp == 1:
				FirstBracket = max(FirstBracket, i - Index.pop() + 1)
			elif temp == 3:
				ThirdBracket = max(ThirdBracket, i - Index.pop() + 1)
	seq = Stack()
	AlterDepth = 0
	curDepth = Stack()
	for i in range(n):
		if (arr[i] == 1 or arr[i] == 3) and seq.empty():
			curDepth.push(1)
			seq.push(arr[i])
			AlterDepth = max(AlterDepth, curDepth.top())
		elif arr[i] == 1 and seq.top() == 3:
			curDepth.push(curDepth.top() + 1)
			seq.push(arr[i])
			AlterDepth = max(AlterDepth, curDepth.top())
		elif arr[i] == 3 and seq.top() == 1:
			curDepth.push(curDepth.top() + 1)
			seq.push(arr[i])
			AlterDepth = max(AlterDepth, curDepth.top())
		elif arr[i] == 1 or arr[i] == 3:
			curDepth.push(curDepth.top())
			seq.push(arr[i])
			AlterDepth = max(curDepth.top(), AlterDepth)
		elif arr[i] == 2 or arr[i] == 4:
			curDepth.pop()
			seq.pop()
	print(AlterDepth, FirstBracket, ThirdBracket)

def __starting_point():
	main()
__starting_point()


n = int(input())
arr = list(map(int, input().split()))
b1 = b2 = maxb1 = maxb2 = b1pos = b2pos = 0
stacklen = 0
stack = []
currtoggle = 0
maxtoggle = 0
for i in range(n):
	if arr[i] == 1:
		if b1 == 0:
			b1pos = i
		b1 += 1
		if currtoggle == 0 or stack[-1] == 3:
			currtoggle += 1
		maxtoggle = max(currtoggle, maxtoggle)
		stack.append(1)
		stacklen += 1
	elif arr[i] == 2:
		b1 -= 1
		if b1 == 0 and i - b1pos + 1 > maxb1:
			maxb1 = i - b1pos + 1
		stack.pop()
		stacklen -= 1
		if stacklen == 0 or stack[-1] == 3:
			currtoggle -= 1
	elif arr[i] == 3:
		if b2 == 0:
			b2pos = i
		b2 += 1
		if currtoggle == 0 or stack[-1] == 1:
			currtoggle += 1
		maxtoggle = max(currtoggle, maxtoggle)
		stack.append(3)
		stacklen += 1
	else:
		b2 -= 1
		if b2 == 0 and i - b2pos + 1 > maxb2:
			maxb2 = i - b2pos + 1
		stack.pop()
		stacklen -= 1
		if stacklen == 0 or stack[-1] == 1:
			currtoggle -= 1
print(maxtoggle, maxb1, maxb2)


import collections

def convertInputToBrackets(arr):
	res = []
	for elem in arr:
		if elem == '1':
			res.append('(')
		elif elem == '2':
			res.append(')')
		elif elem == '3':
			res.append('[')
		elif elem == '4':
			res.append(']')
	return res

def solve(n, arr):
	(balParanthesis, balBrackets) = (0, 0)
	(balParans, balBracks) = ([0], [0])
	stack = []
	(altDepth, maxAltDepth) = (0, 0)
	(maxParanLength, maxBrackLength) = (0, 0)
	for ch in arr:
		if ch == ')' or ch == ']':
			if ch == ')':
				balParanthesis -= 1
			elif ch == ']':
				balBrackets -= 1
			(lastCh, lastAltDepth) = stack.pop()
			maxAltDepth = max(maxAltDepth, lastAltDepth)
		else:
			if ch == '(':
				balParanthesis += 1
			elif ch == '[':
				balBrackets += 1
			if not stack:
				stack.append((ch, 1))
			elif stack[-1][0] != ch:
				stack.append((ch, stack[-1][1] + 1))
			else:
				stack.append(stack[-1])
		balBracks.append(balBrackets)
		balParans.append(balParanthesis)
	(lastParan, lastBrack) = (-1, -1)
	for i in range(n + 1):
		if balBracks[i] == 0:
			maxBrackLength = max(maxBrackLength, i - lastBrack)
			lastBrack = i
		if balParans[i] == 0:
			maxParanLength = max(maxParanLength, i - lastParan)
			lastParan = i
	return ' '.join(map(str, (maxAltDepth, maxParanLength, maxBrackLength)))
n = int(input().strip())
arr = input().strip().split()
arr = convertInputToBrackets(arr)
print(solve(n, arr))


ipnl = lambda n: [int(input()) for _ in range(n)]
inp = lambda : int(input())
ip = lambda : [int(w) for w in input().split()]
n = inp()
x = ip()
(brac, ind) = ([], [])
dt = {2: 0, 4: 0}
for i in range(n):
	if x[i] in [1, 3]:
		brac.append(x[i])
		ind.append(i)
		continue
	dt[x[i]] = max(dt[x[i]], i - ind[-1] + 1)
	ind.pop()
	brac.pop()
alt = 0
(brac, depth) = ([], [])
for i in range(n):
	if (x[i] == 1 or x[i] == 3) and brac == []:
		brac.append(x[i])
		depth.append(1)
		alt = max(alt, depth[-1])
	elif x[i] * brac[-1] == 3:
		brac.append(x[i])
		depth.append(depth[-1] + 1)
		alt = max(alt, depth[-1])
	elif x[i] == 1 or x[i] == 3:
		brac.append(x[i])
		depth.append(depth[-1])
		alt = max(alt, depth[-1])
	elif x[i] == 2 or x[i] == 4:
		brac.pop()
		depth.pop()
print(alt, dt[2], dt[4])


t = int(input())
s = ''
g = []
g = list(map(int, input().split()))
for ele in g:
	if ele == 1:
		s += '('
	elif ele == 2:
		s += ')'
	elif ele == 3:
		s += '['
	else:
		s += ']'
stack = []
deptho = 0
if len(s) > 0:
	deptho = 1
d = {}
d[0] = deptho
d[1] = 0
d[2] = 0
stack = []
depth = []
for i in range(t):
	if len(stack) == 0 and (s[i] == '(' or s[i] == '['):
		stack.append(s[i])
		depth.append(1)
	elif s[i] == '(' and stack[-1] == '[' or (s[i] == '[' and stack[-1] == '('):
		stack.append(s[i])
		depth.append(depth[-1] + 1)
	elif s[i] == '(' or s[i] == '[':
		stack.append(s[i])
		depth.append(depth[-1])
	deptho = max(deptho, depth[-1])
	if s[i] == ')' or s[i] == ']':
		stack.pop()
		depth.pop()
d[0] = deptho
p_char = 0
sq_char = 0
max_sq_char = 0
max_p_char = 0
p_depth = 0
sq_depth = 0
for i in range(t):
	if s[i] == '(':
		p_depth += 1
	if s[i] == '[':
		sq_depth += 1
	if p_depth:
		p_char += 1
	if sq_depth:
		sq_char += 1
	max_sq_char = max(max_sq_char, sq_char)
	max_p_char = max(max_p_char, p_char)
	if s[i] == ')':
		p_depth -= 1
	if s[i] == ']':
		sq_depth -= 1
	if p_depth == 0:
		p_char = 0
	if sq_depth == 0:
		sq_char = 0
d[1] = max_p_char
d[2] = max_sq_char
print(d[0], d[1], d[2])


n = int(input())
a = [int(x) for x in input().split()]
(k, d) = (0, 0)
st = []
st.append(a[0])
(k, d) = (1, 1)
for i in range(1, n):
	if a[i] == 1 or a[i] == 3:
		st.append(a[i])
		if st[len(st) - 1] != st[len(st) - 2]:
			k += 1
			if k > d:
				d += 1
	else:
		try:
			if st[len(st) - 1] != st[len(st) - 2]:
				k -= 1
			st.pop()
		except:
			st.pop()
			k -= 1
(c1, max1) = (0, 0)
s1 = []
for i in range(n):
	try:
		if len(s1) == 0 and a[i] == 1:
			s1.append(a[i])
			c1 += 1
		elif len(s1) != 0 and (a[i] == 1 or a[i] == 3):
			s1.append(a[i])
			c1 += 1
		elif a[i] == 2 or a[i] == 4:
			s1.pop()
			c1 += 1
		if max1 < c1:
			max1 = c1
		if len(s1) == 0:
			c1 = 0
	except:
		pass
(c2, max2) = (0, 0)
s2 = []
for i in range(n):
	try:
		if len(s2) == 0 and a[i] == 3:
			s2.append(a[i])
			c2 += 1
		elif len(s2) != 0 and (a[i] == 1 or a[i] == 3):
			s2.append(a[i])
			c2 += 1
		elif a[i] == 2 or a[i] == 4:
			s2.pop()
			c2 += 1
		if max2 < c2:
			max2 = c2
		if len(s2) == 0:
			c2 = 0
	except:
		pass
print(d, max1, max2)


n = int(input())
it = list(map(int, input().split()))
maa = 0
ma = 0
j = 0
dd = 0
ss = {}
mi = 0
a = []
b = []
for i in it:
	i -= 1
	if i == 1 or i == 3:
		c = a.pop()
		d = b.pop()
		if i == 1:
			maa = max(maa, j - c[1] + 1)
		else:
			mi = max(mi, j - c[1] + 1)
	elif a == []:
		a.append([i, j])
		b.append(1)
	else:
		if i == a[-1][0]:
			b.append(b[-1])
		else:
			b.append(b[-1] + 1)
		a.append([i, j])
	if b:
		ma = max(ma, b[-1])
	j += 1
print(ma, maa, mi)


length = int(input())
brackets = [int(i) for i in input().split()]
alternateDepths = []
(squareSymbols, roundedSymbols) = (0, 0)
(lastAlternatedLevel, lastAlternatedBracket, alDepth, level) = ([None], [None], 0, 0)
(lowestSquareHeight, lowestRoundedHeight) = (float('inf'), float('inf'))
(betweenSquare, betweenRounded) = (0, 0)
for i in brackets:
	if lowestRoundedHeight != float('inf'):
		betweenRounded += 1
	if lowestSquareHeight != float('inf'):
		betweenSquare += 1
	if i in [1, 3]:
		level += 1
		if i != lastAlternatedBracket[-1]:
			alDepth += 1
			lastAlternatedBracket.append(i)
			lastAlternatedLevel.append(level)
		if i == 1 and level < lowestRoundedHeight:
			lowestRoundedHeight = level
			betweenRounded += 1
		elif i == 3 and level < lowestSquareHeight:
			lowestSquareHeight = level
			betweenSquare += 1
	else:
		if i == lastAlternatedBracket[-1] + 1 and level == lastAlternatedLevel[-1]:
			alternateDepths.append(alDepth)
			alDepth -= 1
			lastAlternatedLevel.pop()
			lastAlternatedBracket.pop()
		if i == 2 and level == lowestRoundedHeight:
			if betweenRounded > roundedSymbols:
				roundedSymbols = betweenRounded
			lowestRoundedHeight = float('inf')
			betweenRounded = 0
		if i == 4 and level == lowestSquareHeight:
			if betweenSquare > squareSymbols:
				squareSymbols = betweenSquare
			lowestSquareHeight = float('inf')
			betweenSquare = 0
		level -= 1
print(max(alternateDepths), roundedSymbols, squareSymbols)


def solution(s, op, cl):
	if op not in s:
		return 0
	st = []
	le = mle = 0
	for c in s:
		if c == op:
			st.append(c)
		if c == cl:
			st.pop()
		le += 1
		if not st:
			if le > mle:
				mle = le
			le = 0
	return mle

def altdepth(s):
	pre = []
	dep = []
	ma = 0
	for c in s:
		if c == ')' or c == ']':
			pre.pop()
			dep.pop()
			continue
		if not pre:
			pre.append(c)
			dep.append(1)
		elif c != pre[-1]:
			pre.append(c)
			dep.append(dep[-1] + 1)
		else:
			pre.append(c)
			dep.append(dep[-1])
		if dep:
			ma = max(ma, dep[-1])
	return ma
n = int(input())
x = '()[]'
s = ''.join((x[i - 1] for i in list(map(int, input().split()))))
print(altdepth(s), solution(s, '(', ')'), solution(s, '[', ']'))


n = int(input())
a = list(map(int, input().split()))
k = 0
l = 0
ans1 = 0
ans2 = 0
b = 0
c = 0
mark1 = 0
mark2 = 0
for i in range(0, n):
	if a[i] == 1 and mark1 == 0:
		b += 1
		k = i
		mark1 = 1
	elif a[i] == 1:
		b += 1
	elif a[i] == 2 and b == 1:
		b -= 1
		k = i - k + 1
		ans1 = max(ans1, k)
		mark1 = 0
	elif a[i] == 2:
		b -= 1
	elif a[i] == 3 and mark2 == 0:
		c += 1
		l = i
		mark2 = 1
	elif a[i] == 3:
		c += 1
	elif a[i] == 4 and c == 1:
		c -= 1
		l = i - l + 1
		ans2 = max(ans2, l)
		mark2 = 0
	elif a[i] == 4:
		c -= 1

def alt_solve(s):
	pre = []
	dep = []
	ma = 0
	for c in s:
		if c == 2 or c == 4:
			pre.pop()
			dep.pop()
			continue
		if not pre:
			pre.append(c)
			dep.append(1)
		elif c != pre[-1]:
			pre.append(c)
			dep.append(dep[-1] + 1)
		else:
			pre.append(c)
			dep.append(dep[-1])
		if dep:
			ma = max(ma, dep[-1])
	return ma
print(alt_solve(a), ans1, ans2)


input()
brackets = list(map(int, input().split()))
depth = 0
rn_longest = 0
sq_longest = 0
alt_depth = 0
max_alt_depth = 0
last_alt = (alt_depth, 1 if brackets[0] == 3 else 3)
same_rep = [0]
sq_start = (-2, 0)
rn_start = (-2, 0)
for i in range(len(brackets)):
	b = brackets[i]
	if b in [1, 3]:
		depth += 1
		if b != last_alt[1]:
			alt_depth += 1
			last_alt = (alt_depth, b)
			max_alt_depth = max(alt_depth, max_alt_depth)
			same_rep += [0]
		else:
			same_rep[-1] += 1
		if sq_start[0] == -2 and b == 3:
			sq_start = (i - 1, depth - 1)
		elif rn_start[0] == -2 and b == 1:
			rn_start = (i - 1, depth - 1)
	else:
		depth -= 1
		if b == last_alt[1] + 1:
			if same_rep[-1] > 0:
				same_rep[-1] -= 1
			else:
				alt_depth -= 1
				last_alt = (alt_depth, 1 if b == 4 else 3)
				same_rep.pop(-1)
		if sq_start[1] == depth and b == 4:
			sq_longest = max(sq_longest, i - sq_start[0])
			sq_start = (-2, 0)
		elif rn_start[1] == depth and b == 2:
			rn_longest = max(rn_longest, i - rn_start[0])
			rn_start = (-2, 0)
	if depth == 0:
		if i < len(brackets) - 1:
			last_alt = (alt_depth, 1 if brackets[i + 1] == 3 else 3)
print(max_alt_depth, rn_longest, sq_longest)


def solve(s, op, cl):
	st = []
	le = mle = 0
	for c in s:
		if c == op:
			st.append(c)
		if c == cl:
			st.pop()
		le += 1
		if not st:
			if le > mle:
				mle = le
			le = 0
	return mle

def alt_solve(s):
	pre = []
	dep = []
	ma = 0
	for c in s:
		if (c == '(' or c == '[') and pre == []:
			pre.append(c)
			dep.append(1)
		elif c == '(' and pre[-1] == '[' or (c == '[' and pre[-1] == '('):
			pre.append(c)
			dep.append(dep[-1] + 1)
		elif c == '(' or c == '[':
			pre.append(c)
			dep.append(dep[-1])
		elif c == ')' or c == ']':
			pre.pop()
			dep.pop()
		if dep:
			ma = max(ma, dep[-1])
	return ma
n = int(input())
x = '()[]'
s = ''.join((x[i - 1] for i in list(map(int, input().split()))))
print(alt_solve(s), solve(s, '(', ')'), solve(s, '[', ']'))


n = int(input())
br = [int(i) for i in input().split()]
n = len(br)
alt_count = 0
prev_alt = -1
max_alt = 0
flag1 = flag2 = 0
start1 = start2 = max1 = max2 = 0
help_arr = [[0, 0]]
for i in range(n):
	if br[i] == 1:
		if flag1 == 0:
			start1 = i
		flag1 += 1
	elif br[i] == 2:
		flag1 -= 1
		if flag1 == 0 and i - start1 > max1:
			max1 = i - start1
	elif br[i] == 3:
		if flag2 == 0:
			start2 = i
		flag2 += 1
	elif br[i] == 4:
		flag2 -= 1
		if flag2 == 0 and i - start2 > max2:
			max2 = i - start2
	x = 0
	if br[i] == 1 or br[i] == 3:
		if help_arr[-1][1] != br[i]:
			x = 1
		help_arr.append([help_arr[-1][0] + x, br[i]])
		if help_arr[-1][0] > max_alt:
			max_alt = help_arr[-1][0]
	else:
		help_arr.pop(-1)
if 1 not in br:
	max1 = -1
if 3 not in br:
	max2 = -1
print(max_alt, max1 + 1, max2 + 1)


n = int(input())
a = list(map(int, input().split()))
q = []
temp = 0
depth = 0
bracket = [0, 0]
brac_count = [0, 0]
brac_ind = [0, 0]
for (i, v) in enumerate(a):
	if v == 1 or v == 3:
		if v == 1:
			if brac_count[0] == 0:
				brac_ind[0] = i
			brac_count[0] += 1
		else:
			if brac_count[1] == 0:
				brac_ind[1] = i
			brac_count[1] += 1
		if not q or v != q[-1]:
			temp += 1
		q.append(v)
	else:
		depth = max(temp, depth)
		if len(q) < 2 or q[-1] != q[-2]:
			temp -= 1
		q.pop()
		if v == 2:
			brac_count[0] -= 1
			if brac_count[0] == 0:
				bracket[0] = max(bracket[0], i - brac_ind[0] + 1)
		else:
			brac_count[1] -= 1
			if brac_count[1] == 0:
				bracket[1] = max(bracket[1], i - brac_ind[1] + 1)
print(depth, bracket[0], bracket[1])


def max_len_between(s, paren_type):
	st = []
	length = 0
	max_length = 0
	op = paren_type[0]
	cp = paren_type[1]
	for c in s:
		if c == op:
			st.append(c)
		elif c == cp:
			st.pop()
		if len(st) == 0:
			if length > max_length:
				max_length = length + 1
			length = 0
		else:
			length += 1
	return max_length

def parser(arr):
	return [{1: '(', 2: ')', 3: '[', 4: ']'}[c] for c in arr]
n = int(input())
a = list(map(int, input().split()))
br = []
dep = []
ret = 0
for i in range(0, n):
	if (a[i] == 1 or a[i] == 3) and br == []:
		br.append(a[i])
		dep.append(1)
		ret = max(ret, dep[-1])
	elif a[i] == 1 and br[-1] == 3:
		br.append(a[i])
		dep.append(dep[-1] + 1)
		ret = max(ret, dep[-1])
	elif a[i] == 3 and br[-1] == 1:
		br.append(a[i])
		dep.append(dep[-1] + 1)
		ret = max(ret, dep[-1])
	elif a[i] == 1 or a[i] == 3:
		br.append(a[i])
		dep.append(dep[-1])
		ret = max(ret, dep[-1])
	elif a[i] == 2 or a[i] == 4:
		br.pop()
		dep.pop()
print(ret, max_len_between(parser(a), '()'), max_len_between(parser(a), '[]'))