# Search Range in Binary Search Tree

{% embed url="<https://www.lintcode.com/problem/11/>" %}

## Solution 1 (Java)

```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 {

    private List<Integer> res;
    
    /**
     * @param root: param root: The root of the binary search tree
     * @param k1: An integer
     * @param k2: An integer
     * @return: return: Return all keys that k1<=key<=k2 in ascending order
     */
    public List<Integer> searchRange(TreeNode root, int k1, int k2) {
        res = new ArrayList<Integer>();
        searchRangeHelper(root, k1, k2);
        return res;
    }

    private void searchRangeHelper(TreeNode root, int k1, int k2) {
        if (root == null)
            return;

        // similar to inorder traversal to ensure ascending order
        if (root.val > k1)
            searchRangeHelper(root.left, k1, k2);
        if (root.val >= k1 && root.val <= k2)
            res.add(root.val);
        if (root.val < k2)
            searchRangeHelper(root.right, k1, k2);
    }
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://blog.yushunchen.com/algo/binary-tree/3.-binary-search-tree/search-range-in-binary-search-tree.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.