/**
 * 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.val > p.val && root.val < q.val){
            return root;  
        }else if(root.val>p.val && root.val > q.val){
            return lowestCommonAncestor(root.left, p, q);
        }else if(root.val<p.val && root.val < q.val){
            return lowestCommonAncestor(root.right, p, q);
        }
     
        return root;
    }
}

Create Lowest_Common_Ancestor_of_a_Binary_Search_Tree.java