【LeetCode从零单刷】Gray Code

题目：

The gray code is a binary numeral system where two successive values differ in only one bit.

Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.

For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:

00 - 001 - 111 - 310 - 2

解答：

每次只能改变一次二进制位。说实话看答案之前，完全不知道怎么做。

class Solution {public:    vector<int> grayCode(int n) {        vector<int> ans(1<<n);        for (int i=0; i<(1<<n); i++)             ans[i] = i^(i>>1);        return ans;    }};