22. Extract Even Bits Only from 32-bit Register

#include <stdio.h>
#include <stdint.h>

uint32_t extract_even_bits(uint32_t reg) {
    // Your code here
    uint32_t dup = reg & 0x55555555;
    int count=0;
    while(dup>0) {
        if(dup&1){
            count++;
        }
        dup >>=1;
    }
    
    return ((1<<count)-1);
}

int main() {
    uint32_t reg;
    scanf("%u", &reg);
    printf("%u", extract_even_bits(reg));
    return 0;
}