位运算

https://leetcode.com/problems/gray-code/description/
这个位运算的解法厉害了....

class Solution {
public:
    vector<int> grayCode(int n) {
        int size = 1<<n;//nums of the total;
        vector<int> res;

        for(int i = 0;i<size;i++){
            res.push_back((i>>1) ^ i);    
        }
        return res;
    }
};

int n = n / 2 等价于 int n = n >> 1