190. 颠倒二进制位 Java版

public class Solution {
    // you need treat n as an unsigned value
    public int reverseBits(int n) {

        int ans = 0;

        for(int i = 0; i<32; i++){

            //二进制最后一位bit
            int bit = n&1;

            n = n >> 1;

            ans = (ans << 1) + bit;
        }

        return ans;
    }
}