Arrange given numbers to form the biggest number | Set 2 - GeeksforGeeks

04 Jun, 2020
Given an array of non-negative numbers(of Integer Range), they are needed to be arranged in some order such that it gives the max number. For example given array is A[1, 34, 3, 98, 9, 76, 45, 4, 12, 121]. if we arrange these numbers in the following order, A[9, 98, 76, 45, 4, 34, 3, 12, 121, 1], then by joining them we get “99876454343121211” as largest number.
Examples:
Input :  [1, 34, 3, 98, 9, 76, 45, 4, 12, 121]
Output : 99876454343121211

Input :  [12, 121]
Output : 12121

In SET 1, we have discussed an approach to do same. In this set, we will discuss another logic.
1) Find number of digits in the largest number. Let number of digits be n.2) Create extended version of all numbers. In extended version, we have n+1 digits formed by concatenating the number of with itself and truncating extra digits.3) Sort original numbers according to their extended values.4) Concatenating the sorted numbers produces th required result.
Java
Python
// Java program to arrange the numbers to form the// largest numberimport java.math.BigInteger;import java.util.*;  public class LargestNumber{    // method that returns largest number form    public static String largestNumber(List<Integer> arr)    {        // finding number of digits in maximum element        // present in array        int n =         Collections.max(arr).toString().length();          ArrayList<ExtendedNum> en =                       new ArrayList<ExtendedNum>();        for (int i = 0 ; i < arr.size(); i++)            en.add(new ExtendedNum(arr.get(i),                              n));          // sort based on modified value        Collections.sort(en, (p1, p2) ->         (int)(p2.modifiedValue - p1.modifiedValue));          StringBuilder sb = new StringBuilder();        for (int i = 0; i < en.size(); i++)            sb.append(new StringBuilder            (Long.toString(en.get(i).originalValue)));            // To remove any zeroes at head.        BigInteger bi = new BigInteger(sb.toString());          return bi.toString();    }      // Driver method    public static void main(String[] args)    {        Integer arr[] = {1, 34, 3, 98, 9, 76, 45,                                     4, 12, 121};        List<Integer> l = Arrays.asList(arr);          System.out.println(largestNumber(l));    }}  // A utility class to generate new valueclass ExtendedNum{    int originalValue;    long modifiedValue;      public ExtendedNum(int originalValue, int n)    {        this.originalValue = originalValue;        String s = Integer.toString(originalValue);        StringBuilder sb = new StringBuilder(s);        StringBuilder ans = new StringBuilder();        while (ans.length() <= n + 1)            ans.append(sb);          s = ans.toString().substring(0, n + 1);        modifiedValue = Long.parseLong(s);    }      public String toString()    {        return "[" + modifiedValue +                ", " + originalValue + "]";    }}
# Python program to find largest# number from the given values# function that return largest# possible numberdef largestNumber(array):          # extval is a empty list for extended     # values and ans for calculating answer    extval, ans = [], ""          # calculating the length of largest number    # from given and add 1 for further operation    l = len(str(max(array))) + 1          # iterate given values and     # calculating extended values    for i in array:        temp = str(i) * l                  # make tuple of extended value and         # equivalant original value then         # append to list        extval.append((temp[:l:], i))          # sort extval in descending order    extval.sort(reverse = True)          # iterate extended values    for i in extval:                  # concatinate original value equivalant        # to extended value into ans variable        ans += str(i[1])      if int(ans)==0:        return "0"    return ans  # Driver codea = [1, 34, 3, 98, 9, 76,        45, 4, 12, 121]  print(largestNumber(a))  # This code is contributed by Chhekur
99876454343121211

This article is contributed by Kondiparthi Shanmukha Sarath. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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Chhekur
Galld
number-digits
Arrays
Arrays
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