---恢复内容开始---
题目描述：
方法一：层次遍历
""" # Definition for a Node. class Node: def __init__(self, val, left, right, next): self.val = val self.left = left self.right = right self.next = next """ class Solution: def connect(self, root: 'Node') -> 'Node': if not root: return stack = [root] #ans = [] while stack: tem_stack=[] #tem_ans = [] for i in stack: tem_ans.append(i.val) if i.left: tem_stack.append(i.left) if i.right: tem_stack.append(i.right) if len(tem_stack)>1: for i in range(len(tem_stack)-1): tem_stack[i].next = tem_stack[i+1] stack = tem_stack #ans.append(tem_ans) return root
方法二：迭代
class Solution: def connect(self, root: 'Node') -> 'Node': cur = root head = None tail = None while cur: while cur: if cur.left: if not head: head = cur.left tail = cur.left else: tail.next = cur.left tail = tail.next if cur.right: if not head: head = cur.right tail = cur.right else: tail.next = cur.right tail = tail.next cur = cur.next cur = head head = None tail = None return root
---恢复内容结束---