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 as00111001011110000010100101000000).

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

 

Analyse:

Extract the right-most bit every time, then put it at the corresponding left place in m.

Pay attention to the place of m = (m<<1)

 1 class Solution {
 2 public:
 3     uint32_t reverseBits(uint32_t n) {
 4         uint32_t m = 0;
 5         for(int i = 0; i < 32; i++){
 6             m = (m << 1);
 7             m = (n & 1) | m;
 8             n = (n >> 1);
 9         }
10         return m;
11     }
12 };