1. Gray Code My Submissions QuestionEditorial Solution

   Total Accepted: 60277 Total Submissions: 165212 Difficulty: Medium

   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.

格雷码的数学公式为n⊕(n2)

class Solution {
public:
    vector<int> grayCode(int n) {
        int size = 1<<n;
        vector<int> res;
        res.reserve(size);
        for(int i=0;i<size;++i)
        {
            res.push_back(i^(i>>1));
        }
        return res;
    }
};