Lowest Common Ancestor of a Binary Search Tree

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

According to the definition of LCA: "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)."

Test Cases

Copy an input into the main harness and Run to verify

Input

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

Expected Output

6

Input

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

Expected Output

2

Explanation: Node 2 is an ancestor of 4, so it is the LCA.

Constraints

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.

Hints

Hint 1 — click to reveal

In a BST, values left of a node are smaller, right are larger.

Hint 2 — click to reveal

The LCA is the first node where p and q split to different sides.

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