LeetCode in Python 102. Binary Tree Level Order Traversal
2020-12-13 06:16
标签：log bsp pytho root tps return pen 队列实现 its Given a binary tree, return the level order traversal of its nodes‘ values. (ie, from left to right, level by level). For example: return its level order traversal as: Solution: 最经典的队列实现BFS，注意size是作为for循环次数的依据，Python的 for node in q 的循环不适用，因为q在动态变化。 N-ary的树可参考559（https://www.cnblogs.com/lowkeysingsing/p/11152751.html） LeetCode in Python 102. Binary Tree Level Order Traversal 标签：log bsp pytho root tps return pen 队列实现 its 原文地址：https://www.cnblogs.com/lowkeysingsing/p/11172103.html
Given binary tree [3,9,20,null,null,15,7], 3
/ 9 20
/ 15 7
[
[3],
[9,20],
[15,7]
]
# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def levelOrder(self, root):
"""
:type root: TreeNode
:rtype: List[List[int]]
"""
q, res = root and [root], []
while q:
size, level_path = len(q), []
for i in range(size):
node = q.pop(0)
level_path.append(node.val)
if node.left:
q.append(node.left)
if node.right:
q.append(node.right)
res.append(level_path)
return res
文章标题：LeetCode in Python 102. Binary Tree Level Order Traversal
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