22. Extract Even Bits Only from 32-bit Register

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

uint32_t extract_even_bits(uint32_t x) {
    // Your code here
    
    x = x & 0x55555555;              // keep only even bits
    x = (x | (x >> 1)) & 0x33333333; // compress every 2 bits
    x = (x | (x >> 2)) & 0x0F0F0F0F; // compress every 4 bits
    x = (x | (x >> 4)) & 0x00FF00FF; // compress every 8 bits
    x = (x | (x >> 8)) & 0x0000FFFF;
    return x;
}

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