十六. 位运算

​​461. 汉明距离​​

class Solution:
    def hammingDistance(self, x, y):
        return bin(x ^ y).count('1')

​​面试题 05.03. 翻转数位​​

class Solution:
    def reverseBits(self, num: int) -> int:
        num = bin(num) if num >= 0 else bin(((1 << 32) - 1) & num)
        n = num.split("0")
        ans = -1 
        for i in range(1, len(n)):
            ans = max(ans, n[i-1].count("1") + n[i].count("1") + 1)
        return min(32, ans)

​​231. 2 的幂​​

class Solution:
    def isPowerOfTwo(self, n: int) -> bool:
        return n > 0 and n & (n-1) == 0
        # n 二进制最高位为 1，其余所有位为 0；n−1 二进制最高位为 0，其余所有位为 1

​​1290. 二进制链表转整数​​

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def getDecimalValue(self, head: ListNode) -> int:
        cur = head
        res = 0
        while cur:
            # res = res * 2 + cur.val
            res = (res<<1) + cur.val
            cur = cur.next
        return res