# Insert Node in a Binary Search Tree

## Problem

Given a binary search tree and a new tree node, insert the node into the tree. You should keep the tree still be a valid binary search tree.

## Example

Given binary search tree as follow, after Insert node 6, the tree should be:

      2             2
/ \           / \
1   4   -->   1   4
/             / \
3             3   6

## Challenge

Can you do it without recursion?

## Code - Java

/**
* Definition of TreeNode:
* public class TreeNode {
*   public int val;
*   public TreeNode left, right;
*   public TreeNode(int val) {
*     this.val = val;
*     this.left = this.right = null;
*   }
* }
*/
public class Solution {
/**
* @param root: The root of the binary search tree.
* @param node: insert this node into the binary search tree
* @return: The root of the new binary search tree.
*/
public TreeNode insertNode(TreeNode root, TreeNode node) {
if (root == null) {
return node;
}
if (node.val > root.val) {
if (root.right == null) {
root.right = node;
} else {
insertNode(root.right, node);
}
} else if (node.val < root.val) {
if (root.left == null) {
root.left = node;
} else {
insertNode(root.left, node);
}
}
return root;
}
}