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Sort an array of large numbers

  • Difficulty Level : Medium
  • Last Updated : 03 Sep, 2021

Given an array of numbers where every number is represented as string. The numbers may be very large (may not fit in long long int), the task is to sort these numbers.
Examples: 
 

Input : arr[] = {"5", "1237637463746732323", "12" };
Output : arr[] = {"5", "12", "1237637463746732323"};

Input : arr[] = {"50", "12", "12", "1"};
Output : arr[] = {"1", "12", "12", "50"};

Below is the implementation of the above idea.
 

C++




// C++ program to sort large numbers represented
// as strings.
#include<bits/stdc++.h>
using namespace std;
 
// Returns true if str1 is smaller than str2.
bool compareNumbers(string str1, string str2)
{
    // Calculate lengths of both string
    int n1 = str1.length(), n2 = str2.length();
 
    if (n1 < n2)
       return true;
    if (n2 < n1)
       return false;
 
    // If lengths are same
    for (int i=0; i<n1; i++)
    {
       if (str1[i] < str2[i])
          return true;
       if (str1[i] > str2[i])
          return false;
    }
 
    return false;
}
 
// Function for sort an array of large numbers
// represented as strings
void sortLargeNumbers(string arr[], int n)
{
   sort(arr, arr+n, compareNumbers);
}
 
// Driver code
int main()
{
    string arr[] = {"5", "1237637463746732323",
                    "97987", "12" };
    int n = sizeof(arr)/sizeof(arr[0]);
 
    sortLargeNumbers(arr, n);
 
    for (int i=0; i<n; i++)
      cout << arr[i] << " ";
 
    return 0;
}

Java




// Java program to sort large numbers represented
// as strings.
import java.io.*;
import java.util.*;
 
class main
{
    // Function for sort an array of large numbers
    // represented as strings
    static void sortLargeNumbers(String arr[])
    {
        // Refer below post for understanding below expression:
        Arrays.sort(arr, (left, right) ->
        {
            /* If length of left != right, then return
               the diff of the length else  use compareTo
               function to compare values.*/
            if (left.length() != right.length())
                return left.length() - right.length();
             return left.compareTo(right);
        });
    }
 
    // Driver code
    public static void main(String args[])
    {
        String arr[] = {"5", "1237637463746732323",
                        "97987", "12" };
        sortLargeNumbers(arr);
        for (String s : arr)
            System.out.print(s + " ");
    }
}

Python3




# Python3 program to sort large numbers
# represented as strings
 
# Function for sort an array of large
# numbers represented as strings
def sortLargeNumbers (arr, n):
 
    arr.sort(key = int)
 
# Driver Code
if __name__ == '__main__':
 
    arr = [ "5", "1237637463746732323",
            "97987", "12" ]
    n = len(arr)
 
    sortLargeNumbers(arr, n)
 
    for i in arr:
        print(i, end = ' ')
     
# This code is contributed by himanshu77

C#




// C# program to sort large numbers
// represented as strings.
using System;
 
class GFG
{
 
    // Function for sort an array of large
    // numbers represented as strings
    static void sortLargeNumbers(String []arr)
    {
        // Refer below post for understanding 
        // below expression:
        for(int i = 0; i < arr.Length - 1; i++)
        {
            /* If length of left != right, then
            return the diff of the length else
            use compareTo function to compare values.*/
            String left = arr[i], right = arr[i + 1];
            if (left.Length > right.Length)
            {
                arr[i] = right;
                arr[i + 1] = left;
                i -= 2;
            }
        }
    }
 
    // Driver code
    public static void Main()
    {
        String []arr = {"5", "1237637463746732323",
                        "97987", "12" };
        sortLargeNumbers(arr);
        foreach (String s in arr)
            Console.Write(s + " ");
    }
}
 
// This code is contributed by PrinciRaj1992

Javascript




<script>
 
// JavaScript program to sort large numbers
// represented as strings.
 
    // Function for sort an array of large numbers
    // represented as strings
    function sortLargeNumbers(arr)
    {
         // Refer below post for understanding 
        // below expression:
        for(let i = 0; i < arr.length - 1; i++)
        {
            /* If length of left != right, then
            return the diff of the length else
            use compareTo function to compare values.*/
            let left = arr[i], right = arr[i + 1];
            if (left.length > right.length)
            {
                arr[i] = right;
                arr[i + 1] = left;
                i -= 2;
            }
        }
    }
 
// Driver Code
     let arr = ["5", "1237637463746732323",
                        "97987", "12" ];
        sortLargeNumbers(arr);
        for (let s in arr)
            document.write(arr[s] + " ");
 
</script>

Output:  

5 12 97987 1237637463746732323 

Time complexity: O(k * n Log n) where k is length of the longest number. Here assumption is that the sort() function uses a O(n Log n) sorting algorithm.
Similar Post: 
Sorting Big Integers
This article is contributed by DANISH KALEEM. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
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