标签：style blog http java color strong
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.
https://oj.leetcode.com/problems/gray-code/
思路：格雷码的 定义
思路：递归生成码表法。
思路2：公式法。gray = (binary) xor (binary >> 1)
import java.util.ArrayList; import java.util.List; public class Solution { public List<Integer> grayCode(int n) { List<Integer> res = new ArrayList<Integer>(); if (n == 0) { res.add(0); return res; } List<Integer> pre = grayCode(n - 1); res.addAll(pre); int high = 1 << n - 1; for (int i = pre.size() - 1; i >= 0; i--) res.add(high + pre.get(i)); return res; } public List<Integer> grayCode2(int n) { List<Integer> res = new ArrayList<Integer>(); int count = 1 << n; for (int i = 0; i < count; i++) { res.add(i ^ (i >> 1)); } return res; } public static void main(String[] args) { System.out.println(new Solution().grayCode(3)); } }
参考：
http://blog.csdn.net/worldwindjp/article/details/21536103
[leetcode] Gray Code,布布扣,bubuko.com
标签：style blog http java color strong
原文地址：http://www.cnblogs.com/jdflyfly/p/3819281.html
