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Count of integers in an Array whose length is a multiple of K

  • Last Updated : 27 May, 2021

Given an array arr of N elements and an integer K, the task is to count all the elements whose length is a multiple of K.
Examples: 
 

Input: arr[]={1, 12, 3444, 544, 9}, K = 2
Output: 2
Explanation:
There are 2 numbers whose digit count is multiple of 2 {12, 3444}.

Input: arr[]={12, 345, 2, 68, 7896}, K = 3
Output: 1
Explanation:
There is 1 number whose digit count is multiple of 3 {345}.

 

Approach: 
 

  1. Traverse the numbers in the array one by one
  2. Count the digits of every number in the array
  3. Check if its digit count is a multiple of K or not.

Below is the implementation of above approach: 
 

C++




// C++ implementation of above approach
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find
// digit count of numbers
int digit_count(int x)
{
    int sum = 0;
    while (x) {
        sum++;
        x = x / 10;
    }
    return sum;
}
 
// Function to find the count of numbers
int find_count(vector<int> arr, int k)
{
 
    int ans = 0;
    for (int i : arr) {
 
        // Get the digit count of each element
        int x = digit_count(i);
 
        // Check if the digit count
        // is divisible by K
        if (x % k == 0)
 
            // Increment the count
            // of required numbers by 1
            ans += 1;
    }
 
    return ans;
}
 
// Driver code
int main()
{
    vector<int> arr
        = { 12, 345, 2, 68, 7896 };
    int K = 2;
 
    cout << find_count(arr, K);
 
    return 0;
}

Java




// Java implementation of above approach
 
class GFG{
  
// Function to find
// digit count of numbers
static int digit_count(int x)
{
    int sum = 0;
    while (x > 0) {
        sum++;
        x = x / 10;
    }
    return sum;
}
  
// Function to find the count of numbers
static int find_count(int []arr, int k)
{
  
    int ans = 0;
    for (int i : arr) {
  
        // Get the digit count of each element
        int x = digit_count(i);
  
        // Check if the digit count
        // is divisible by K
        if (x % k == 0)
  
            // Increment the count
            // of required numbers by 1
            ans += 1;
    }
  
    return ans;
}
  
// Driver code
public static void main(String[] args)
{
    int []arr = { 12, 345, 2, 68, 7896 };
    int K = 2;
  
    System.out.print(find_count(arr, K));
  
}
}
 
// This code is contributed by 29AjayKumar

Python3




# Python3 implementation of above approach
 
# Function to find
# digit count of numbers
def digit_count(x):
    sum = 0
    while (x):
        sum += 1
        x = x // 10
    return sum
 
# Function to find the count of numbers
def find_count(arr,k):
    ans = 0
    for i in arr:
        # Get the digit count of each element
        x = digit_count(i)
 
        # Check if the digit count
        # is divisible by K
        if (x % k == 0):
            # Increment the count
            # of required numbers by 1
            ans += 1
 
    return ans
 
# Driver code
if __name__ == '__main__':
    arr  =  [12, 345, 2, 68, 7896]
    K = 2
 
    print(find_count(arr, K))
 
# This code is contributed by Surendra_Gangwar

C#




// C# implementation of above approach
 
using System;
 
public class GFG{
 
// Function to find
// digit count of numbers
static int digit_count(int x)
{
    int sum = 0;
    while (x > 0) {
        sum++;
        x = x / 10;
    }
    return sum;
}
 
// Function to find the count of numbers
static int find_count(int []arr, int k)
{
 
    int ans = 0;
    foreach (int i in arr) {
 
        // Get the digit count of each element
        int x = digit_count(i);
 
        // Check if the digit count
        // is divisible by K
        if (x % k == 0)
 
            // Increment the count
            // of required numbers by 1
            ans += 1;
    }
 
    return ans;
}
 
// Driver code
public static void Main(String[] args)
{
    int []arr = { 12, 345, 2, 68, 7896 };
    int K = 2;
 
    Console.Write(find_count(arr, K));
 
}
}
 
// This code is contributed by Rajput-Ji

Javascript




<script>
 
// JavaScript implementation of above approach
 
// Function to find
// digit count of numbers
function digit_count(x)
{
    let sum = 0;
    while (x) {
        sum++;
        x = x / 10;
    }
    return sum;
}
 
// Function to find the count of numbers
function find_count(arr, k)
{
 
    let ans = 0;
    for (let i of arr) {
 
        // Get the digit count of each element
        let x = digit_count(i);
 
        // Check if the digit count
        // is divisible by K
        if (x % k == 0)
 
            // Increment the count
            // of required numbers by 1
            ans += 1;
    }
 
    return ans;
}
 
// Driver code
 
let arr = [ 12, 345, 2, 68, 7896 ];
let K = 2;
 
document.write(find_count(arr, K));
 
// This code is contributed by _saurabh_jaiswal
 
</script>
Output: 



3

 

Time complexity:- O(N*M), where N is the size of array, and M is the digit count of the largest number in the array. 
Space complexity:- O(1)
 

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