235.py

# https://neetcode.io/problems/lowest-common-ancestor-in-binary-search-tree
# https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/description/

# Definition for a binary tree node.
class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

class Solution:
    def lowestCommonAncestor(self, root: TreeNode, p: TreeNode, q: TreeNode) -> TreeNode:
        if not root:
            return None
        if min(p.val, q.val) <= root.val and root.val <= max(p.val, q.val):
            return root
        if root.val > max(p.val, q.val):
            return self.lowestCommonAncestor(root.left, p, q)
        if root.val < min(p.val, q.val):
            return self.lowestCommonAncestor(root.right, p, q)