0653.two-sum-iv-input-is-a-bst

653. Two Sum IV - Input is a BST

题目

Given a Binary Search Tree and a target number, return true if there exist two elements in the BST such that their sum is equal to the given target.

Example 1:

Input:
    5
   / \
  3   6
 / \   \
2   4   7

Target = 9

Output: True

Example 2:

Input:
    5
   / \
  3   6
 / \   \
2   4   7

Target = 28

Output: False

解题思路

见程序注释