[Leetcode]@python 89. Gray Code

题目链接

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

题目原文

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

题目大意

给出一个非负数，返回从0到这个数的格雷码

解题思路

格雷码的生成，采用数学的方法
https://zh.wikipedia.org/wiki/格雷码

代码

class Solution(object):
    def grayCode(self, n):
        """
        :type n: int
        :rtype: List[int]
        """
        ans = []
        size = 1 << n
        for i in range(size):
            ans.append((i >> 1) ^ i)
        return ans