653. Two Sum IV - Input is a BST

https://leetcode.com/problems/two-sum-iv-input-is-a-bst/

Python

DFS

• Remember the path and do postorder traversal
• Did NOT use the advantage from BST...

class Solution:
    def findTarget(self, root: Optional[TreeNode], k: int) -> bool:
        def dfs(node, targets: set):
            if not node:
                return False
            if node.val in targets:
                return True

            targets.add(k-node.val)

            return dfs(node.left, targets) or dfs(node.right, targets)

        return dfs(root, set())