leetcode 236. Lowest Common Ancestor of a Binary Tree | 236. 二叉树的最近公共祖先（Java）

港控/mmm° 2022-10-09 02:57 158阅读 0赞

## 题目 ##

[https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/][https_leetcode.com_problems_lowest-common-ancestor-of-a-binary-tree]  
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## 题解 ##

> 思路来源：左程云《程序员代码面试指南》

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_1_color_FFFFFF_t_70]

/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */
    class Solution { 
        public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) { 
            if (root == null || root == p || root == q) return root;
            TreeNode l = lowestCommonAncestor(root.left, p, q);
            TreeNode r = lowestCommonAncestor(root.right, p, q);
            if (l != null && r != null) return root;
            else if (r != null) return r;
            else return l;
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]

[https_leetcode.com_problems_lowest-common-ancestor-of-a-binary-tree]: https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx_size_16_color_FFFFFF_t_70 1]: /images/20221005/f96403c58fd24b8590c5852acbec6334.png