Compress Interleaved Bits Reverse Bit Spreading

Code

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

uint8_t compress_bits(uint16_t val) {
    // Your logic here
    uint16_t mask16=1, k;
    uint8_t i, mask8=1, reg=0;
    
    for (i=0; i < 8; i++) {
        k = (val & mask16);
        if (k != 0) {
            reg = reg | mask8;
        }
        mask8 = mask8 << 1;
        mask16 = mask16 << 2;
    }
    return reg;
}

int main() {
    uint16_t val;
    scanf("%hu", &val);

    uint8_t result = compress_bits(val);
    printf("%u", result);
    return 0;
}

Solving Approach

run a mask on the 16-bit value and another on the 8-bit result to set or clear the bits as required.