python-leetcode-填充每个节点的下一个右侧节点指针 II

117. 填充每个节点的下一个右侧节点指针 II - 力扣（LeetCode）

"""
# Definition for a Node.
class Node:def __init__(self, val: int = 0, left: 'Node' = None, right: 'Node' = None, next: 'Node' = None):self.val = valself.left = leftself.right = rightself.next = next
"""
from collections import dequeclass Solution:def connect(self, root: 'Node') -> 'Node':if not root:return Nonequeue = deque([root])while queue:size = len(queue)prev = None  # 记录上一节点for i in range(size):node = queue.popleft()if prev:prev.next = node  # 连接前一个节点的 nextprev = node  # 更新 previf node.left:queue.append(node.left)if node.right:queue.append(node.right)# 该层最后一个节点的 next 置为 Noneprev.next = Nonereturn root