Sort the numbers according to their product of digits

Given an array arr[] of N non-negative integers, the task is to sort these integers according to the product of their digits.
Examples:

Input: arr[] = {12, 10, 102, 31, 15} 
Output: 10 102 12 31 15 
10 -> 1 * 0 = 0 
102 -> 1 * 0 * 2 = 0 
12 -> 1 * 2 = 2 
31 -> 3 * 1 = 3 
15 -> 1 * 5 = 5
Input: arr[] = {12, 10} 
Output: 10 12 

Approach: The idea is to store each element with its product of digits in a vector pair and then sort all the elements of the vector according to the digit products stored. Finally, print the elements in order.
Below is the implementation of the above approach: 

C++

// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;

// Function to return the product
// of the digits of n
int productOfDigit(int n)
{
    int product = 1;
    while (n > 0) {
        product *= n % 10;
        n = n / 10;
    }
    return product;
}

// Function to sort the array according to
// the product of the digits of elements
void sortArr(int arr[], int n)
{
    // Vector to store the digit product
    // with respective elements
    vector<pair<int, int> > vp;

    // Inserting digit product with elements
    // in the vector pair
    for (int i = 0; i < n; i++) {
        vp.push_back(make_pair(productOfDigit(arr[i]), arr[i]));
    }

    // Sort the vector, this will sort the pair
    // according to the product of the digits
    sort(vp.begin(), vp.end());

    // Print the sorted vector content
    for (int i = 0; i < vp.size(); i++)
        cout << vp[i].second << " ";
}

// Driver code
int main()
{
    int arr[] = { 12, 10, 102, 31, 15 };
    int n = sizeof(arr) / sizeof(arr[0]);

    sortArr(arr, n);

    return 0;
}

Java

// Java implementation of the
// above approach
import java.util.*;

class GFG {

  // Function to return the product
  // of the digits of n
  static int productOfDigit(int n)
  {
    int product = 1;
    while (n > 0) {
      product *= n % 10;
      n /= 10;
    }
    return product;
  }

  // Function to sort the array according to
  // the product of the digits of elements
  static void sortArr(int[] arr, int n)
  {
    // Vector to store the digit product
    // with respective elements
    ArrayList<ArrayList<Integer> > vp
      = new ArrayList<ArrayList<Integer> >();
    // Loop to create 2D array using 1D array
    for (int i = 0; i < n; i++) {
      vp.add(new ArrayList<Integer>());
    }

    // Inserting digit product with elements
    // in the vector pair
    for (int i = 0; i < n; i++) {
      ArrayList<Integer> l1 = vp.get(i);
      l1.add(productOfDigit(arr[i]));
      l1.add(arr[i]);
      vp.set(i, l1);
    }

    // Sort the vector, this will sort the pair
    // according to the product of the digits
    Collections.sort(
      vp, new Comparator<ArrayList<Integer> >() {
        public int compare(ArrayList<Integer> o1,
                           ArrayList<Integer> o2)
        {
          if (o1.get(0) != o2.get(0))
            return o1.get(0).compareTo(
            o2.get(0));
          return o1.get(1).compareTo(o2.get(1));
        }
      });

    // Print the sorted vector content
    for (int i = 0; i < n; i++)
      System.out.print(vp.get(i).get(1) + " ");
  }

  // Driver code
  public static void main(String[] args)
  {
    int[] arr = { 12, 10, 102, 31, 15 };
    int n = arr.length;
    sortArr(arr, n);
  }
}

// This code is contributed by phasing17

Python3

# Python3 implementation of the approach

# Function to return the product
# of the digits of n
def productOfDigit(n) :

    product = 1;
    while (n > 0) :
        product *= (n % 10);
        n = n // 10;

    return product;

# Function to sort the array according to
# the product of the digits of elements
def sortArr(arr, n) :

    # Vector to store the digit product
    # with respective elements
    vp = [];

    # Inserting digit product with elements
    # in the vector pair
    for i in range(n) :
        vp.append((productOfDigit(arr[i]), arr[i]));

    # Sort the vector, this will sort the pair
    # according to the product of the digits
    vp.sort();

    # Print the sorted vector content
    for i in range(len(vp)) :
        print(vp[i][1], end = " ");

# Driver code
if __name__ == "__main__" :

    arr = [ 12, 10, 102, 31, 15 ];
    n = len(arr);

    sortArr(arr, n);

# This code is contributed by AnkitRai01

C#

// C# implementation of the
// above approach
using System;
using System.Linq;
using System.Collections.Generic;

class GFG
{

  // Function to return the product
  // of the digits of n
  static int productOfDigit(int n)
  {
    int product = 1;
    while (n > 0) {
      product *= n % 10;
      n /= 10;
    }
    return product;
  }

  // Function to sort the array according to
  // the product of the digits of elements
  static void sortArr(int[] arr, int n)
  {
    // Vector to store the digit product
    // with respective elements
    List<List<int> > vp = new List<List<int> >();
    // Loop to create 2D array using 1D array
    for (var i = 0; i < n; i++) {
      vp.Add(new List<int>());
    }

    // Inserting digit product with elements
    // in the vector pair
    for (var i = 0; i < n; i++) {
      vp[i].Add(productOfDigit(arr[i]));
      vp[i].Add(arr[i]);
    }

    // Sort the vector, this will sort the pair
    // according to the product of the digits
    vp = vp.OrderBy(x => x[0])
      .ThenBy(x => x[1])
      .ToList();

    // Print the sorted vector content
    for (int i = 0; i < n; i++)
      Console.Write(vp[i][1] + " ");
  }

  // Driver code
  public static void Main(string[] args)
  {
    int[] arr = { 12, 10, 102, 31, 15 };
    int n = arr.Length;
    sortArr(arr, n);
  }
}

// This code is contributed by phasing17

Javascript

<script>
// Javascript implementation of the
// above approach

// Function to return the product
// of the digits of n
function productOfDigit(n)
{
    var product = 1;
    while (n > 0) {
        product *= n % 10;
        n = Math.floor(n / 10);
    }
    return product;
}

// Function to sort the array according to
// the product of the digits of elements
function sortArr(arr, n)
{
    // Vector to store the digit product
    // with respective elements
    var vp = new Array(n);
    // Loop to create 2D array using 1D array
    for (var i = 0; i < vp.length; i++) {
        vp[i] = [];
    }

    // Inserting digit product with elements
    // in the vector pair
    for (var i = 0; i < n; i++) {
        vp[i].push(productOfDigit(arr[i]));
        vp[i].push(arr[i]);
    }

    // Sort the vector, this will sort the pair
    // according to the product of the digits
    vp.sort();

    // Print the sorted vector content
    for (var i = 0; i < n; i++)
        document.write(vp[i][1] + " ");
}

// Driver code
var arr = [ 12, 10, 102, 31, 15];
var n = arr.length;
sortArr(arr, n);

// This code is contributed by ShubhamSingh10
</script>

Output:

10 102 12 31 15

Time Complexity: O(nlogn)

Auxiliary Space: O(n), since n extra space has been taken.