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 evens = 0U;
    uint32_t filtered = reg & 0x55555555U;

    for(int i = 0; i < 16; i++){
        if((filtered >> (2 * i)) & 1U){
            evens = evens << 1;
            evens += 1U;
        }
    }
    return evens;
}

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