Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as 00111001011110000010100101000000).

Follow up:

If this function is called many times, how would you optimize it?

Related problem:

Credits:

Special thanks to for adding this problem and creating all test cases.

Analysis:

Shift result to left by 1 bit, get the last bit of n, put the bit onto result.

Solution:

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