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
    reg &= 0x55555555;
    reg = (reg & 0x33333333) |((reg>>1) & 0x33333333);
    reg = (reg & 0xf0f0f0f)  |((reg>>2) & 0xf0f0f0f);
    reg = (reg & 0xff00ff)   |((reg>>4) & 0xff00ff);
    reg = (reg & 0xffff)     |((reg>>8) & 0xffff);
    return reg;
}

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