# 235. Lowest Common Ancestor of a Binary Search Tree (Easy)

https://leetcode.com/problems/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).”

Given binary search tree:  root = [6,2,8,0,4,7,9,null,null,3,5] 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.

## Solutions

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
class Solution {
public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {

// Value of current node or parent node.
int parentVal = root.val;

// Value of p
int pVal = p.val;

// Value of q;
int qVal = q.val;

if (pVal > parentVal && qVal > parentVal) {
// If both p and q are greater than parent
return lowestCommonAncestor(root.right, p, q);
} else if (pVal < parentVal && qVal < parentVal) {
// If both p and q are lesser than parent
return lowestCommonAncestor(root.left, p, q);
} else {
// We have found the split point, i.e. the LCA node.
return root;
}
}
}
``````