22. Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t reg) {
    uint32_t even_bits = 0;
    for(unsigned int i = 0; i < 16; i++) {
        even_bits |= (reg & 1U) << i;
        reg >>= 2;
    }

    return even_bits;
}

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