[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.

Reference:

class Solution
{
public:
/*
* for reference: http://en.wikipedia.org/wiki/Gray_code. */
vector<int> grayCode(int n)
{
vector<int> ret;
int size = 1 << n;
for(int i = 0; i < size; ++i)
ret.push_back((i >> 1)^i);
return ret;
}
};