190. 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

反转01串

C++（4ms）：

 1 class Solution {
 2 public:
 3     uint32_t reverseBits(uint32_t n) {
 4         uint32_t res = 0 ;
 5         for(int i = 0 ; i < 32 ; i++){
 6             res = (res<<1) + (n>>i & 1) ;
 7         }
 8         return res ;
 9     }
10 };