1+ /*
2+ Author: King, wangjingui@outlook.com
3+ Date: Dec 27, 2014
4+ Problem: Gray Code
5+ Difficulty: Easy
6+ Source: https://oj.leetcode.com/problems/gray-code/
7+ Notes:
8+ The gray code is a binary numeral system where two successive values differ in only one bit.
9+ Given a non-negative integer n representing the total number of bits in the code, print the
10+ sequence of gray code. A gray code sequence must begin with 0.
11+ For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:
12+ 00 - 0
13+ 01 - 1
14+ 11 - 3
15+ 10 - 2
16+ Note:
17+ For a given n, a gray code sequence is not uniquely defined.
18+ For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.
19+ For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.
20+
21+ Solution: Refer to http://en.wikipedia.org/wiki/Gray_code.
22+ */
23+ public class Solution {
24+ public List <Integer >grayCode (int n ) {
25+ ArrayList <Integer >res =new ArrayList <Integer >();
26+ for (int i =0 ;i <1 <<n ; ++i )
27+ res .add ((int )((i >>1 ) ^i ));
28+ return res ;
29+ }
30+ }
