Count array elements having sum of digits equal to K

Given an array arr[] of size N, the task is to count the number of array elements whose sum of digits is equal to K.

Examples:

Input: arr[] = {23, 54, 87, 29, 92, 62}, K = 11
Output: 2
Explanation: 
29 = 2 + 9 = 11
92 = 9 + 2 = 11

Input: arr[]= {11, 04, 57, 99, 98, 32}, K = 18
Output: 1

Approach: Follow the steps below to solve the problem:

• Initialize a variable, say N, to store the size of the array.
• Initialize a variable, say count, to store the elements having sum of digits equal to K.
• Declare a function, sumOfDigits() to calculate the sum of digits of a number.
• Traverse the array arr[] and for each array element, check if the sum of digits is equal to K or not. If found to be true, then increment count by 1.
• Print the value of count as the required answer.

Below is the implementation of the above approach:

C++

// C++ program for the above approach

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

// Function to calculate the
// sum of digits of the number N
int sumOfDigits(int N)
{
    // Stores the sum of digits
    int sum = 0;
    while (N != 0) {
        sum += N % 10;
        N /= 10;
    }

    // Return the sum
    return sum;
}

// Function to count array elements
int elementsHavingDigitSumK(int arr[], int N, int K)
{
    // Store the count of array
    // elements having sum of digits K
    int count = 0;

    // Traverse the array
    for (int i = 0; i < N; ++i) {

        // If sum of digits is equal to K
        if (sumOfDigits(arr[i]) == K) {

            // Increment the count
            count++;
        }
    }

    // Print the count
    cout << count;
}

// Driver Code
int main()
{
    // Given array
    int arr[] = { 23, 54, 87, 29, 92, 62 };

    // Given value of K
    int K = 11;

    // Size of the array
    int N = sizeof(arr) / sizeof(arr[0]);

    // Function call to count array elements
    // having sum of digits equal to K
    elementsHavingDigitSumK(arr, N, K);

    return 0;
}

Java

// Java program for the above approach
public class GFG
{

    // Function to calculate the
    // sum of digits of the number N
    static int sumOfDigits(int N)
    {

        // Stores the sum of digits
        int sum = 0;
        while (N != 0) {
            sum += N % 10;
            N /= 10;
        }

        // Return the sum
        return sum;
    }

    // Function to count array elements
    static void elementsHavingDigitSumK(int[] arr, int N, int K)
    {

        // Store the count of array
        // elements having sum of digits K
        int count = 0;

        // Traverse the array
        for (int i = 0; i < N; ++i)
        {

            // If sum of digits is equal to K
            if (sumOfDigits(arr[i]) == K)
            {

                // Increment the count
                count++;
            }
        }

        // Print the count
        System.out.println(count);
    }

  // Driver code
  public static void main(String args[])
  {

    // Given array
    int[] arr = { 23, 54, 87, 29, 92, 62 };

    // Given value of K
    int K = 11;

    // Size of the array
    int N = arr.length;

    // Function call to count array elements
    // having sum of digits equal to K
    elementsHavingDigitSumK(arr, N, K);
  }
}

// This code is contributed by AnkThon

Python3

# Python3 program for the above approach

# Function to calculate the
# sum of digits of the number N
def sumOfDigits(N) :

    # Stores the sum of digits
    sum = 0
    while (N != 0) :
        sum += N % 10
        N //= 10

    # Return the sum
    return sum

# Function to count array elements
def elementsHavingDigitSumK(arr, N, K) :

    # Store the count of array
    # elements having sum of digits K
    count = 0

    # Traverse the array
    for i in range(N):

        # If sum of digits is equal to K
        if (sumOfDigits(arr[i]) == K) :

            # Increment the count
            count += 1

    # Print the count
    print(count)

# Driver Code

# Given array
arr = [ 23, 54, 87, 29, 92, 62 ]

# Given value of K
K = 11

# Size of the array
N = len(arr)

# Function call to count array elements
# having sum of digits equal to K
elementsHavingDigitSumK(arr, N, K)

# This code is contributed by souravghosh0416.

C#

// C# program for the above approach
using System;
using System.Collections.Generic;
class GFG {

    // Function to calculate the
    // sum of digits of the number N
    static int sumOfDigits(int N)
    {

        // Stores the sum of digits
        int sum = 0;
        while (N != 0) {
            sum += N % 10;
            N /= 10;
        }

        // Return the sum
        return sum;
    }

    // Function to count array elements
    static void elementsHavingDigitSumK(int[] arr, int N, int K)
    {
        // Store the count of array
        // elements having sum of digits K
        int count = 0;

        // Traverse the array
        for (int i = 0; i < N; ++i) {

            // If sum of digits is equal to K
            if (sumOfDigits(arr[i]) == K) {

                // Increment the count
                count++;
            }
        }

        // Print the count
        Console.WriteLine(count);
    }

  // Driver code
  static void Main()
  {

    // Given array
    int[] arr = { 23, 54, 87, 29, 92, 62 };

    // Given value of K
    int K = 11;

    // Size of the array
    int N = arr.Length;

    // Function call to count array elements
    // having sum of digits equal to K
    elementsHavingDigitSumK(arr, N, K);
  }
}

// This code is contributed by divyeshrabadiya07.

Javascript

<script>

    // JavaScript program for the above approach

    // Function to calculate the
    // sum of digits of the number N
    function sumOfDigits(N)
    {

        // Stores the sum of digits
        let sum = 0;
        while (N != 0) {
            sum += N % 10;
            N = parseInt(N / 10, 10);
        }

        // Return the sum
        return sum;
    }

    // Function to count array elements
    function elementsHavingDigitSumK(arr, N, K)
    {
        // Store the count of array
        // elements having sum of digits K
        let count = 0;

        // Traverse the array
        for (let i = 0; i < N; ++i) {

            // If sum of digits is equal to K
            if (sumOfDigits(arr[i]) == K) {

                // Increment the count
                count++;
            }
        }

        // Print the count
        document.write(count);
    }

    // Given array
    let arr = [ 23, 54, 87, 29, 92, 62 ];

    // Given value of K
    let K = 11;

    // Size of the array
    let N = arr.length;

    // Function call to count array elements
    // having sum of digits equal to K
    elementsHavingDigitSumK(arr, N, K);

</script>

Output:

2

Time Complexity: O(N * logN)
Auxiliary Space: O(1)