Search in a Binary Search Tree — LeetCode 700 Python Solution

The problem

You are given the root of a binary search tree (BST) and an integer val. Find the node in the BST that the node's value equals val and return the subtree rooted with that node.

Example

Input

root = [4,2,7,1,3], val = 2

Output

[2,1,3]

Python solution

# 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 searchBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
        if root is None or root.val == val:
            return root
        return (
            self.searchBST(root.left, val)
            if root.val > val
            else self.searchBST(root.right, val)
        )

Complexity

Pattern: Tree Traversal

Choose the order — preorder, inorder, postorder, level — and the problem solves itself. LeetCode 700. Search in a Binary Search Tree is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Tree, Binary Tree and Binary Search Tree.

The tree traversal guide has the Python template for the pattern and the 225 LeetCode problems that use it.

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