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# Get Keys In Binary Search Tree In Given Range

Get the list of keys in a given binary search tree in a given range\[min, max] in ascending order, both min and max are inclusive.

**Examples**

        5

      /    \\

    3        8

  /   \        \\

 1     4        11

get the keys in \[2, 5] in ascending order, result is  \[3, 4, 5]

**Corner Cases**

* What if there are no keys in the given range? Return an empty list in this case.

**How is the binary tree represented?**

We use the level order traversal sequence with a special symbol "#" denoting the null node.

**For Example:**

The sequence \[1, 2, 3, #, #, 4] represents the following binary tree:

    1

  /   \\

 2     3

      /

    4

```
public class Solution {
  List<Integer> result = new ArrayList();

  public List<Integer> getRange(TreeNode root, int min, int max) {
    if (root == null) return new ArrayList();
    //base case 

    //recusive rule
    //check left child valid?
    //check self valid?
    //check right child valid?
    //return result
    getRange(root.left, min, max);

    int key = root.key;
    if (min <= key && key <= max){
      result.add(key);
    }

    getRange(root.right, min , max);
    
    return result;
  }
}

```