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: 

 

 

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 };