24. Keep Only the Highest Set Bit

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

uint16_t highest_set_bit(uint16_t reg) {
    if (reg == 0) return 0;

    uint16_t result = 1U << 15; // find the highest set bit.
    while ((reg & result) == 0) {
        result >>= 1;
    }

    return result;
}

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

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