class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {
        
        int result = 0;
        for (int i = 0; i < 32; i++)
        {
            result += n&1;
            n >>>= 1;
            if(i<31)
                result <<= 1;
        }
        return result;
    }
}