Count distinct pairs from two arrays having same sum of digits

Given two arrays arr1[] and arr2[]. The task is to find the total number of distinct pairs(formed by picking 1 element from arr1 and one element from arr2), such that both the elements of the pair have the sum of digits.
Note: Pairs occurring more than once must be counted only once.
Examples: 

Input : arr1[] = {33, 41, 59, 1, 3}
        arr2[] = {3, 32, 51, 3}
Output : 3
Possible pairs are:
(33, 51), (41, 32), (3, 3)

Input : arr1[] = {1, 6, 4, 22}
        arr2[] = {1, 3, 24}
Output : 2
Possible pairs are:
(1, 1), (6, 24)

Approach:

• Run two nested loops to generate all possible pairs from the two arrays taking one element from arr1[] and one from arr2[].
• If sum of digits is equal, then insert the pair(a, b) into a set, in order to avoid duplicates where a is the smaller element and b is the larger one.
• Total pairs will be the size of the final set.

Below is the implementation of the above approach:

C++

// C++ program to count total number of
// pairs having elements with same
// sum of digits

#include <bits/stdc++.h>
using namespace std;

// Function for returning
// sum of digits of a number
int digitSum(int n)
{
    int sum = 0;
    while (n > 0) {
        sum += n % 10;
        n = n / 10;
    }
    return sum;
}

// Function to return the total pairs
// of elements with equal sum of digits
int totalPairs(int arr1[], int arr2[], int n, int m)
{

    // set is used to avoid duplicate pairs
    set<pair<int, int> > s;

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {

            // check sum of digits
            // of both the elements
            if (digitSum(arr1[i]) == digitSum(arr2[j])) {

                if (arr1[i] < arr2[j])
                    s.insert(make_pair(arr1[i], arr2[j]));
                else
                    s.insert(make_pair(arr2[j], arr1[i]));
            }
        }
    }

    // return size of the set
    return s.size();
}

// Driver code
int main()
{
    int arr1[] = { 100, 3, 7, 50 };
    int arr2[] = { 5, 1, 10, 4 };
    int n = sizeof(arr1) / sizeof(arr1[0]);
    int m = sizeof(arr2) / sizeof(arr2[0]);

    cout << totalPairs(arr1, arr2, n, m);
    return 0;
}

Java

// Java program to count total number of
// pairs having elements with same
// sum of digits
import java.util.*;

class GFG
{

static class pair
{
    int first, second;
    public pair(int first, int second)
    {
        this.first = first;
        this.second = second;
    }
}

// Function for returning
// sum of digits of a number
static int digitSum(int n)
{
    int sum = 0;
    while (n > 0)
    {
        sum += n % 10;
        n = n / 10;
    }
    return sum;
}

// Function to return the total pairs
// of elements with equal sum of digits
static int totalPairs(int arr1[], int arr2[],
                      int n, int m)
{

    // set is used to avoid duplicate pairs
    Set<pair> s = new HashSet<>();

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {

            // check sum of digits
            // of both the elements
            if (digitSum(arr1[i]) == digitSum(arr2[j]))
            {
                if (arr1[i] < arr2[j])
                    s.add(new pair(arr1[i], arr2[j]));
                else
                    s.add(new pair(arr2[j], arr1[i]));
            }
        }
    }

    // return size of the set
    return s.size();
}

// Driver code
public static void main(String[] args)
{
    int arr1[] = { 100, 3, 7, 50 };
    int arr2[] = { 5, 1, 10, 4 };
    int n = arr1.length;
    int m = arr2.length;

    System.out.println(totalPairs(arr1, arr2, n, m));
}
}

// This code is contributed by Rajput-Ji

Python3

# Python3 program to count total number of
# pairs having elements with same sum of digits

# Function for returning
# sum of digits of a number
def digitSum(n):

    Sum = 0
    while n > 0:
        Sum += n % 10
        n = n // 10

    return Sum

# Function to return the total pairs
# of elements with equal sum of digits
def totalPairs(arr1, arr2, n, m):

    # set is used to avoid duplicate pairs
    s = set()

    for i in range(0, n):
        for j in range(0, m):

            # check sum of digits
            # of both the elements
            if digitSum(arr1[i]) == digitSum(arr2[j]):

                if arr1[i] < arr2[j]:
                    s.add((arr1[i], arr2[j]))
                else:
                    s.add((arr2[j], arr1[i]))

    # return size of the set
    return len(s)

# Driver code
if __name__ == "__main__":

    arr1 = [100, 3, 7, 50]
    arr2 = [5, 1, 10, 4]
    n = len(arr1)
    m = len(arr2)

    print(totalPairs(arr1, arr2, n, m))

# This code is contributed by Rituraj Jain

C#

// C# program to count total number of
// pairs having elements with same
// sum of digits
using System;
using System.Collections.Generic;

class GFG
{

public class pair
{
    public int first, second;
    public pair(int first, int second)
    {
        this.first = first;
        this.second = second;
    }
}

// Function for returning
// sum of digits of a number
static int digitSum(int n)
{
    int sum = 0;
    while (n > 0)
    {
        sum += n % 10;
        n = n / 10;
    }
    return sum;
}

// Function to return the total pairs
// of elements with equal sum of digits
static int totalPairs(int []arr1, int []arr2,
                      int n, int m)
{

    // set is used to avoid duplicate pairs
    HashSet<pair> s = new HashSet<pair>();

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {

            // check sum of digits
            // of both the elements
            if (digitSum(arr1[i]) == digitSum(arr2[j]))
            {
                if (arr1[i] < arr2[j])
                    s.Add(new pair(arr1[i], arr2[j]));
                else
                    s.Add(new pair(arr2[j], arr1[i]));
            }
        }
    }

    // return size of the set
    return s.Count;
}

// Driver code
public static void Main(String[] args)
{
    int []arr1 = { 100, 3, 7, 50 };
    int []arr2 = { 5, 1, 10, 4 };
    int n = arr1.Length;
    int m = arr2.Length;

    Console.WriteLine(totalPairs(arr1, arr2, n, m));
}
}

// This code is contributed by Princi Singh

Javascript

<script>

// Javascript program to count total number of
// pairs having elements with same
// sum of digits

// Function for returning
// sum of digits of a number
function digitSum(n)
{
    var sum = 0;
    while (n > 0) {
        sum += n % 10;
        n = parseInt(n / 10);
    }
    return sum;
}

// Function to return the total pairs
// of elements with equal sum of digits
function totalPairs(arr1, arr2, n, m)
{

    // set is used to avoid duplicate pairs
    var s = new Set();

    for (var i = 0; i < n; i++) {
        for (var j = 0; j < m; j++) {

            // check sum of digits
            // of both the elements
            if (digitSum(arr1[i]) == digitSum(arr2[j])) {

                if (arr1[i] < arr2[j])
                    s.add([arr1[i], arr2[j]]);
                else
                    s.add([arr2[j], arr1[i]]);
            }
        }
    }

    // return size of the set
    return s.size;
}

// Driver code
var arr1 = [100, 3, 7, 50 ];
var arr2 = [5, 1, 10, 4 ];
var n = arr1.length;
var m = arr2.length;
document.write( totalPairs(arr1, arr2, n, m));

</script>

Output:

3