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

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Algorithms

Given the <code>root</code> of a binary search tree and an integer <code>k</code>, return <code>true</code> if there exist two elements in the BST such that their sum is equal to <code>k</code>, or <code>false</code> otherwise.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_1.jpg" style="width: 400px; height: 229px;" />
<pre>
Input: root = [5,3,6,2,4,null,7], k = 9
Output: true
</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_2.jpg" style="width: 400px; height: 229px;" />
<pre>
Input: root = [5,3,6,2,4,null,7], k = 28
Output: false
</pre>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 104]</code>.</li>
	<li><code>-104 &lt;= Node.val &lt;= 104</code></li>
	<li><code>root</code> is guaranteed to be a valid binary search tree.</li>
	<li><code>-105 &lt;= k &lt;= 105</code></li>
</ul>

findTarget

Two Sum IV - Input is a BST

Two Sum

two-sum

两数之和

Two Sum II - Input Array Is Sorted

two-sum-ii-input-array-is-sorted

两数之和 II - 输入有序数组

Two Sum III - Data structure design

two-sum-iii-data-structure-design

两数之和 III - 数据结构设计

Two Sum BSTs

two-sum-bsts

查找两棵二叉搜索树之和

Tree

Depth-First Search

Breadth-First Search

Binary Search Tree

Hash Table

Two Pointers

Binary Tree

给定一个二叉搜索树 <code>root</code> 和一个目标结果 <code>k</code>，如果二叉搜索树中存在两个元素且它们的和等于给定的目标结果，则返回 <code>true</code>。

&nbsp;

示例 1：
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_1.jpg" style="height: 229px; width: 400px;" />
<pre>
输入: root = [5,3,6,2,4,null,7], k = 9
输出: true
</pre>

示例 2：
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/21/sum_tree_2.jpg" style="height: 229px; width: 400px;" />
<pre>
输入: root = [5,3,6,2,4,null,7], k = 28
输出: false
</pre>

&nbsp;

提示:

<ul>
	<li>二叉树的节点个数的范围是&nbsp;&nbsp;<code>[1, 104]</code>.</li>
	<li><code>-104&nbsp;&lt;= Node.val &lt;= 104</code></li>
	<li>题目数据保证，输入的 <code>root</code> 是一棵 有效 的二叉搜索树</li>
	<li><code>-105&nbsp;&lt;= k &lt;= 105</code></li>
</ul>