i ^ (i >> 1), that‘s the general format
1 class Solution { 2 public: 3 vector<int> grayCode(int n) { 4 vector<int> result; 5 for (int i = 0; i < (1 << n); i++) { 6 result.push_back(i ^ (i >> 1)); 7 } 8 return result; 9 } 10 };
LeetCode – Refresh – Gray Code
原文：http://www.cnblogs.com/shuashuashua/p/4352217.html