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

Solution:

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