# LeetCode - 0089. Gray Code
### 題目網址：https://leetcode.com/problems/gray-code/
###### tags: `LeetCode` `Medium` `數學` `位元運算`

/*
    -LeetCode format-
    Problem: 89. Gray Code
    Difficulty: Medium
    
    by Inversionpeter
*/



vector <int> answer;

class Solution {
public:
    vector<int> grayCode(int n) {
        int graycode = 0, amount = 1 << n, index = 0;
        answer.resize(amount);
        while (index < amount) {
            answer[index] = graycode; ++index;
            graycode ^= 1;
            answer[index] = graycode; ++index;
            graycode ^= (graycode & (-graycode)) << 1;
        }
        return answer;
    }
};