leetcode Question 32: Gary code

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.

Analysis:

See this website about the gray code and the binary to gray algorithm.

http://en.wikipedia.org/wiki/Gray_code

Source Code:

class Solution {
public:
    unsigned int binary2gray(unsigned int bi){
        return (bi>>1)^bi;
    }
    vector<int> grayCode(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<int> res;
        for (unsigned int i=0;i<pow(2,n);i++){
            res.push_back(binary2gray(i));
        }
        return res;
    }
};