Count the number of elements in the array. The number of 1's in its binary representation is a multiple of K

The setting bits are the binary representation of 0 and 1. This number 1 is called a setting bit in a computer. Let us take an example to understand the calculation of set bits -

Let us take an example to understand setbit calculation -

The setting bit of the integer 96 is calculated as

Suppose we want to set the bits to a sum of 96. So according to the above representation, we will set bit 1 to those array elements and their sum will be 96. This way we will form 2 groups of bits. So if we set the K value to 2, the setting bits of 96 are multiples of it.

In this program, we will solve the array element counting problem, where the number of set bits is a multiple of K.

algorithm

• We will use a header file named ‘bits/stdc .h’ to start the program, which contains all the standard template libraries of C.

• We are creating a function definition called ‘find_bitcount’, which accepts three parameters, namely arr, n and k, and is defined as follows −

  arr[] − Get the array input from the array's main function.

  n − The length of the array

  k - Checks divisibility with the set bit count.

  This will count the total number of set bits in the array elements.

• We then store ‘0’ into the ‘ans’ variable, which will keep track of the count of numbers that satisfy the condition.

• We start the for loop to iterate each element and store the array element i.e. 'arr[i]' into the variable 'x', which is The condition is met in the following while loop to check the total bit setting count. This function initializes 'x' to the value of the array element.

• Then the variable 'setBitsCount' is initialized to '0', which will track the number of set bits of the current array element.

• Next, we create a while loop to check if x (the array element stored in x) is greater than 0 and do the following:

• setBitsCount = x & 1 − Use the bitwise AND operator and 1 in a loop to determine if the least significant bit of x is 1.

• x = x >> 1 − If the result is 1, increase the set number of digits by 1. Then use the >> operator in the loop to shift x 1 bit to the right to eliminate the least significant bit.

• Now use the if statement to check whether 'setBitsCount' is divisible by 'k', use the '%' operator, and is equal to '0', then the current array element meets the condition and increments the variable 'ans by '1' '.

• After processing all the above conditions, the function returns the value of 'ans', which defines the total number of set digits in the array elements.

• Go ahead and start the main function and declare all the array elements. Then we initialize the variable 'n' to find the size of the array and initialize the variable 'K' to '2' which will check if the array element is K multiples.

• Finally, in the print statement, we call the function definition named 'find_bitcount()' and get the result.

Example

In this program, we will implement counting of an array element whose set bit is a multiple of K.

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

// Function to find the count of numbers
int find_bitcount(int arr[], int n, int k) {
   int ans = 0;
   for (int i = 0; i < n; i++) {
      int x = arr[i];
      int setBitsCount = 0;

      // Calculate the set-bits count of the element x
      while (x > 0) {
         setBitsCount += x & 1;
         x = x >> 1;
      }

      // Check if the setbits count
      // is divisible by K
      if (setBitsCount % k == 0)
      ans++;
   }
   return ans;
}
int main() {
   int arr[] = { 6, 845, 4, 168, 7896 };
   int n = sizeof(arr) / sizeof(arr[0]);
   int K = 2;
   cout << "There are "<<find_bitcount(arr, n, K)<<" array element whose setbits are in a multiple of K";
   return 0;
}

Output

There are 3 array element whose setbits are in a multiple of K

in conclusion

We explored the concept of counting elements of an array, and the number of digits set is a multiple of K. In this program, a function is defined to calculate the total count of elements of a set number of array elements. We then observe how the set number of bits is shifted through the >> operator and use a conditional statement to check how many array elements were passed to the set number of bits. Finally, we simply print the results.

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