Algorithm: Gray Code Gray code

topic

地址：https://leetcode.com/problems/gray-code/
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.

Example 1:

Input: 2
Output: [0,1,3,2]
Explanation:
00 - 0
01 - 1
11 - 3
10 - 2

For a given n, a gray code sequence may not be uniquely defined.
For example, [0,2,3,1] is also a valid gray code sequence.

00 - 0
10 - 2
11 - 3
01 - 1

Example 2:

Input: 0
Output: [0]
Explanation: We define the gray code sequence to begin with 0.
             A gray code sequence of n has size = 2n, which for n = 0 the size is 20 = 1.
             Therefore, for n = 0 the gray code sequence is [0].

Gray Code chart

Decimal	Binary	Gray
0	0000	0000
1	0001	0001
2	0010	0011
3	0011	0010
4	0100	0110
5	0101	0111
6	0110	0101
7	0111	0100
8	1000	1100
9	1001	1101
10	1010	1111
11	1011	1110
12	1100	1010
13	1101	1011
14	1110	1001
15	1111	1000

Traversal achieve

package backtracking;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

// https://leetcode.com/problems/gray-code/
public class GrayCode {

  public static void main(String[] args) {
    GrayCode obj = new GrayCode();
    List<Integer> result = obj.grayCode(2);
    System.out.println(Arrays.toString(result.toArray()));
  }

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

    return result;
  }
}

Download

https://github.com/zgpeace/awesome-java-leetcode/blob/master/code/LeetCode/src/backtracking/GrayCode.java

reference

https://en.wikipedia.org/wiki/Gray_code