30. Count Set Bits in an Integer

#include <stdio.h>

int countSetBits(unsigned int n) {
    int count;
    while (n) {
        n &= (n - 1); //keeps all set bits except the rightmost.
        count++;
    }
    return count;
}

int main() {
    int n;
    scanf("%d", &n);
    printf("%d", countSetBits(n));
    return 0;
}