# Search Range in Binary Search Tree

## Problem

Given two values k1 and k2 (where k1 < k2) and a root pointer to a Binary Search Tree. Find all the keys of tree in range k1 to k2. i.e. print all x such that k1<=x<=k2 and x is a key of given BST. Return all the keys in ascending order.

## Example

If k1 = 10 and k2 = 22, then your function should return [12, 20, 22].

        20
/  \
8   22
/ \
4   12

## 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 k1    and k2: range k1 to k2.
* @return: Return all keys that k1<=key<=k2 in ascending order.
*/
public ArrayList<Integer> searchRange(TreeNode root, int k1, int k2) {
ArrayList<Integer> result = new ArrayList<Integer>();
if (root == null) {
return result;
}
if (root.val > k1) {
}