leetcode-solutions/python/search-in-a-binary-search-tree.py at master · alirezaghey/leetcode-solutions · GitHub

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from typing import Optional


# 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:
    # Time complexity: O(log n)
    # Space complexity: O(1)
    # Iterative
    def searchBST(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
        while root:
            if root.val == val:
                return root
            elif root.val < val:
                root = root.right
            else:
                root = root.left
        return root

    # Time complexity: O(log n)
    # Space complexity: O(log n)
    # Recursive
    def searchBST2(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
        if not root:
            return None

        if root.val == val:
            return root
        if root.val < val:
            return self.searchBST(root.right, val)
        else:
            return self.searchBST(root.left, val)