public class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {
        int shiftCount = 31;
        int reversed = 0b0;

        while (shiftCount >= 0) {
            int digit = n & 1;
            n = n >> 1;
            if (digit == 0b1) {
                reversed = reversed | (digit << shiftCount);
            }
            shiftCount--;
        }

        return reversed;
    }
}

impl Solution {
    pub fn reverse_bits(x: u32) -> u32 {
        let mut shiftCount: i32 = 31;
        let mut reversed: u32 = 0;
        let mut n = x;

        while (shiftCount >= 0) {
            let digit = n & 1;
            if (digit == 1) {
                reversed |= (digit << shiftCount);
            }

            n = n >> 1;
            shiftCount -= 1;
        }

        return reversed;
    }
}