LeetCode 235. Lowest Common Ancestor of a Binary Search Tree

题目

思路

因为是BST，所以可以判断root和p、q的大小关系。

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 lowestCommonAncestor(self, root, p, q):
        """
        :type root: TreeNode
        :type p: TreeNode
        :type q: TreeNode
        :rtype: TreeNode
        """
        if not root or root == p or root == q: return root
        if root.val < p.val and root.val < q.val: return self.lowestCommonAncestor(root.right, p, q)
        if root.val > p.val and root.val > q.val: return self.lowestCommonAncestor(root.left, p, q)
        return root