Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target.
Example 1:
Input: root = [5,3,6,2,4,null,7], k = 9
Output: true
Example 2:
Input: root = [5,3,6,2,4,null,7], k = 28
Output: false
Constraints:
- The number of nodes in the tree is in the range
[1, 104]. -
-104 <= Node.val <= 104 -
rootis guaranteed to be a valid binary search tree. -
-105 <= k <= 105
SOLUTION:
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def inorder(self, root, k):
if root and not self.possible:
self.inorder(root.left, k)
if (k - root.val) in self.exists:
self.possible = True
self.exists.add(root.val)
self.inorder(root.right, k)
def findTarget(self, root: Optional[TreeNode], k: int) -> bool:
self.possible = False
self.exists = set()
self.inorder(root, k)
return self.possible
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