89. Gray Code 解题记录

题目描述：

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 - 0
01 - 1
11 - 3
10 - 2

Note:
For a given n, a gray code sequence is not uniquely defined.

For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.

For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.

解题思路：

格雷码可以直接用二进制码转换，将当前二进制码和左移一位的二进制码异或就可以得到当前二进制码所对应的格雷码。

代码:

class Solution {
public:
    vector<int> grayCode(int n) {
        vector<int> nums;
        for(int i = 0; i < 1 << n; i++){
        //n位对应格雷码一共有1<<n个格雷码
            nums.push_back(i^i>>1);
        }
        return nums;
    }
};