【leetcode】Gray Code

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.

 1 class Solution {
 2 public:
 3   vector<int> grayCode(int n) {
 4         // Start typing your C/C++ solution below
 5         // DO NOT write int main() function
 6         vector<int> res;
 7         res.push_back(0);
 8         int highbit = 0;
 9         while(n--)
10         {
11             highbit = res.size();
12             for(int i= res.size()-1; i >= 0; i--)
13                 res.push_back(highbit|res[i]);
14         }
15         return res;
16     }
17 };

【leetcode】Gray Code

原文：http://www.cnblogs.com/jawiezhu/p/4444704.html