Keep Only the Highest Set Bit

Code

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

// Complete the function
uint16_t highest_set_bit(uint16_t reg) {
    // Your logic here
    uint16_t i, mask=0x8000;
    for (i=0; i<16; i++) {
        if ((reg & mask) !=0) {
            return mask;
        }
        else {
            mask = mask >> 1;
        }
    }
    return mask;
}

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

    uint16_t result = highest_set_bit(reg);
    printf("%hu", result);
    return 0;
}

Solving Approach

start from MSB and look for 1, 

if not found shift right and repeat until exhaust the register.