编程语言:
python
题目:
给你一个二叉树,请你返回其按 层序遍历 得到的节点值。 (即逐层地,从左到右访问所有节点)。
示例:
二叉树:[3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
返回其层次遍历结果:
[
[3],
[9,20],
[15,7]
]
来源:
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/binary-tree-level-order-traversal
解法:
二叉树的广度优先搜索:
代码:
# 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]]
"""
if not root:
return []
res = [[root.val]]
flag = [root]
while flag:
ans = []
for curr in flag:
if curr.left:
ans.append(curr.left)
if curr.right:
ans.append(curr.right)
if ans:
res.append([i.val for i in ans])
flag = ans
return res