# Facebook Mülakat Sorusu – Lowest Common Ancestor of a Binary Search Tree

Leetcode içerisinde bulunan “Lowest Common Ancestor of a Binary Search Tree” sorusunun açıklaması ve çözümü. Bu soruda size verilen bir binary search tree içerisinde, verilen iki tane TreeNode’un en aşağıdaki ortak parent’ını bulmanız isteniyor. Bence deneme olarak bunun iterative halini de siz yazabilirsiniz.

► LeetCode 235. Lowest Common Ancestor of a Binary Search Tree: https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/

► Problem açıklaması:

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.

According to the definition of LCA on Wikipedia:

“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).”

Example 1:

Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8

Output: 6

Explanation: The LCA of nodes 2 and 8 is 6.

Example 2:

Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4

Output: 2

Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.

Example 3:

Input: root = [2,1], p = 2, q = 1

Output: 2

Constraints:

The number of nodes in the tree is in the range [2, 105].

-109 <= The number of nodes in the tree is in the range [2, 10^5].

-10^9 <= Node.val <= 10^9

All Node.val are unique.

p != q

p and q will exist in the BST.

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