Count all prefixes of the given binary array which are divisible by x in C++

In this tutorial, we will be discussing a program to find the number of prefixes of the binary array which are divisible by x.

For this we will be provided with binary array and a value x. Our task is to find the number of elements whose prefixes are divisible by given value x.

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
//counting the elements with prefixes
//divisible by x
int count_divx(int arr[], int n, int x){
   int number = 0;
   int count = 0;
   for (int i = 0; i < n; i++) {
      number = number * 2 + arr[i];
      //increasing count
      if ((number % x == 0))
         count += 1;
   }
   return count;
}
int main(){
   int arr[] = { 1, 0, 1, 0, 1, 1, 0 };
   int n = sizeof(arr) / sizeof(arr[0]);
   int x = 2;
   cout << count_divx(arr, n, x);
   return 0;
}

Output

3