[leetcode-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?
思路：

随时移位，用异或代替相加。

uint32_t reverseBits(uint32_t n)
     {
         uint32_t m = 0;
         
         for (int i = 0; i < 32;i++)
         {
             m <<= 1;
             m += n & 1;
             n >>= 1;
         }
         return m;
     }