Keep Only the Highest Set Bit

Code

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

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

    // Shift right until only one bit remains
    while (reg & (reg - 1)) {
        reg &= (reg - 1);  // clear lowest set bit each time
    }

    return reg;
}

int main() {
    uint16_t reg;
    scanf("%hu", &reg);
    printf("%hu", keep_highest_bit(reg));
    return 0;
}

Solving Approach