Medium

Quiz

#235 Lowest Common Ancestor of a Binary Search Tree

APPROACH

Given a binary search tree (BST), locate the lowest common ancestor (LCA) of two given nodes p and q.

The LCA is the deepest node that has both p and q as descendants (a node counts as its own descendant).

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

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What is the optimal approach for this problem?