[LeetCode] Reverse Bits

Question：

Reverse bits of a given 32 bits unsigned integer.

For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as00111001011110000010100101000000).

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

1、题型分类：

2、思路：

3、时间复杂度：

4、代码：

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

　　注意加粗部分，先移位还是先或的区别！

5、优化：

6、扩展：