LeetCode 089 Gray Code

题目描述

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.

分析

将数字i，转换成格雷码的公式是：(i >> 1) ^ i

代码

    public static List<Integer> grayCode(int n) {        List<Integer> result = new ArrayList<Integer>();        if (n < 0) {            return result;        }        for (int i = 0; i < Math.pow(2, n); i++) {            result.add((i >> 1) ^ i);        }        return result;    }