Gray Code

题目

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.

方法

格雷编码的生成，i >> 1 ^ i 即可。

public List<Integer> grayCode(int n) {
List<Integer> list = new ArrayList<Integer>();
int len = 1 << n;
for (int i = 0; i < len ; i++) {
int g = (i >> 1) ^ i;
list.add(g);
}
return list;
}