# Search Range

``````如果有 k1 = 10 和 k2 = 22, 你的程序应该返回 [12, 20, 22].

20
/  \
8   22
/ \
4   12
``````

## Code

``````/**
* 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> res = searchRangeRecur(root,k1,k2);
return res;
}

public ArrayList<Integer> searchRangeRecur(TreeNode cur, int k1, int k2){
ArrayList<Integer> res = new ArrayList<Integer>();
if (cur==null) return res;
if (k1>k2) return res;

ArrayList<Integer> left = searchRangeRecur(cur.left,k1,Math.min(cur.val-1,k2));
ArrayList<Integer> right = searchRangeRecur(cur.right,Math.max(cur.val+1,k1),k2);