leetcode-86-格雷编码

class Solution:
    def grayCode(self, n: int) -> List[int]:
        gray = [0]
        for i in range(n):
            add = 2**i
            for j in range(len(gray)-1,-1,-1):
                gray.append(add+gray[j])
        return gray

class Solution: 
    def grayCode(self, n: int) -> List[int]: 
        res = [] 
        for i in range(2 ** n): 
            res.append((i >> 1) ^ i) 
        return res