Gray Code

Change-Id: I7fb8879b76fb1a712e5f63ed8e74209563c79d56

Author: applewjg

GrayCode.java

@@ -0,0 +1,30 @@
+/*
+ Author:     King, [email protected]
+ Date:       Dec 27, 2014
+ Problem:    Gray Code
+ Difficulty: Easy
+ Source:     https://oj.leetcode.com/problems/gray-code/
+ Notes:
+ 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.
+
+ Solution: Refer to http://en.wikipedia.org/wiki/Gray_code.
+ */
+public class Solution {
+    public List<Integer> grayCode(int n) {
+        ArrayList<Integer> res = new ArrayList<Integer>();
+        for (int i = 0; i < 1 << n; ++i)
+            res.add((int)((i >> 1) ^ i));
+        return res;     
+    }
+}