LeetCode236-二叉树的最近公共祖先

原题链接：https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/

相同题：

LeetCode235：https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree/

剑指offer68-I：https://leetcode-cn.com/problems/er-cha-sou-suo-shu-de-zui-jin-gong-gong-zu-xian-lcof/

剑指offer68-II：https://leetcode-cn.com/problems/er-cha-shu-de-zui-jin-gong-gong-zu-xian-lcof/

 

解题思路：树形DP

代码：

 1 # Definition for a binary tree node.
 2 # class TreeNode:
 3 #     def __init__(self, x):
 4 #         self.val = x
 5 #         self.left = None
 6 #         self.right = None
 7 
 8 # case1: p是q的lca or q是p的lca
 9 # case2: p和q不互为lca，都向上遍历找到
10 class Solution:
11     def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
12         # base case
13         if not root or root == p or root == q:
14             return root
15         left = self.lowestCommonAncestor(root.left, p, q)
16         right = self.lowestCommonAncestor(root.right, p, q)
17         # 命中case2，不命中case1
18         if left and right:
19             return root
20         # 命中case1，不命中case2
21         if left:
22             return left
23         else:
24             return right

 

posted @ 2022-01-13 23:33  CaptainDragonfly  阅读(22)  评论(0)  编辑  收藏  举报