Leetcode: Reverse Bits

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: Reverse Integer

 1 public class Solution {
 2     // you need treat n as an unsigned value
 3     public int reverseBits(int n) {
 4         int res = 0;
 5         for (int i=0; i<32; i++) {
 6             int bit = (n>>i) & 1;
 7             res |= bit<<(31-i); 
 8         }
 9         return res;
10     }
11 }