LeetCode Gray Code

来源：互联网发布：华中地区数据科学会议编辑：程序博客网时间：2024/04/29 00:41

Description:

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 - 001 - 111 - 310 - 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:

首先将0到2^n - 1的数字对应的二进制得到，然后通过

公式表示：

（G：格雷码，B：二进制码）

公式，将二进制的数字转化为格雷码，最高位（位数从0到n-1)，第n位补0，再将最后得到的格雷码当作二进制数字，转化为十进制。

import java.util.*;public class Solution {List<Integer> list = new ArrayList<Integer>();public List<Integer> grayCode(int n) {if (n == 0) {list.add(0);return list;}String binary, grey;int limit = 1 << n;for (int i = 0; i < (1 << n); i++) {binary = Integer.toBinaryString((limit - 1) & i | limit);binary = "0" + binary.substring(1);grey = "";for (int j = 1; j < binary.length(); j++) {grey = grey+ ((binary.charAt(j - 1) - '0') ^ (binary.charAt(j) - '0'));}list.add(Integer.parseInt(grey, 2));}return list;}public static void main(String[] args) {Solution s = new Solution();s.grayCode(3);}}

0 0