LCA on BST recursive

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

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

      // both p and q are less than root
      // their ancestor must be in root.left
      if (p.val < root.val && q.val < root.val)
        return lowestCommonAncestor(root.left, p, q);

      // both p and q are greater than root
      // their ancestor must be in root.right
      if (p.val > root.val && q.val > root.val)
        return lowestCommonAncestor(root.right, p, q);

      return root;
    }

  }