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 comp=0;
    uint16_t reg_new=0;
    for (int i = 0; i <= 17; i++)
    {
        comp = (1<<i);
        if (comp > reg)
        {
           reg_new |= (1<<(i-1));
           return reg_new;
        }
        else if (reg == 65535)
        {
            reg_new |= (1<<15);
            return reg_new;
        }
    }
    return 0;
}

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

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

Solving Approach

Track when 2**i is greater than reg, when true, last most bit is i-1. Account for when reg is max 16 bit value.