37 lines
1.3 KiB
Markdown
37 lines
1.3 KiB
Markdown
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Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
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According to the [definition of LCA on Wikipedia](https://en.wikipedia.org/wiki/Lowest_common_ancestor): “The lowest common ancestor is defined between two nodes `p` and `q` as the lowest node in `T` that has both `p` and `q` as descendants (where we allow **a node to be a descendant of itself**).”
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**Example 1:**
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Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
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Output: 6
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Explanation: The LCA of nodes 2 and 8 is 6.
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**Example 2:**
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Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
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Output: 2
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Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
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**Example 3:**
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Input: root = [2,1], p = 2, q = 1
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Output: 2
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**Constraints:**
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* The number of nodes in the tree is in the range `[2, 105]`.
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* `-109 <= Node.val <= 109`
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* All `Node.val` are **unique**.
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* `p != q`
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* `p` and `q` will exist in the BST.
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https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree
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