Reference: LeetCode

Difficulty: Easy

## Problem

Given a Binary Search Tree and a target number, return

`true`

if there existtwo elementsin the BST such that their sum is equal to the given target.

**Example:**

1 | Input: |

## Analysis

### Hash Set

Using any traversal is fine.

**Note:** Duplicates are allowed.

1 | public boolean findTarget(TreeNode root, int k) { |

**Time:** $O(N)$**Space:** $O(N)$

### Inorder + Two Pointers

Basically, we convert the BST tree to a sorted list and then apply the two-pointer method.

**Time:** $O(N)$**Space:** $O(N)$