190. Reverse Bits

题目：

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?

答案：

就是二进制倒置，用位运算解决

class Solution {
public:
    uint32_t reverseBits(uint32_t n) {
        uint32_t r=0;
        for(int i=0;i<32;i++){
            r=r<<1;
            r=r|(n&1);
            n=n>>1;
        }
        return r;
    }
};