Lowest Common Ancestor of a Binary Search Tree

LeetCode Q 235- Lowest Common Ancestor of a Binary Search Tree

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.

Note:

• All of the nodes’ values will be unique.
• p and q are different and both values will exist in the BST.

Solution:

Code:

public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
  if (root == null) return null;

  if (p.val > q.val) return lowestCommonAncestor(root, q, p);

  while (!(root.val > p.val && root.val < q.val)) {
    if (root.val < p.val) root = root.right;
    if (root.val > q.val) root = root.left;
  }

  return root;
}