30. Count Set Bits in an Integer

How do you plan to solve it?

#include <stdio.h>
int countSetBits(unsigned int n) {
   int count = 0;
   while (n) {
       count += n & 1;
       n >>= 1;
   }
   return count;
}
int main() {
   int n;
   scanf("%d", &n);
   printf("%d\n", countSetBits(n));
   return 0;
}