sum-of-nodes-with-even-valued-grandparent

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Algorithms

Given the <code>root</code> of a binary tree, return the sum of values of nodes with an even-valued grandparent. If there are no nodes with an even-valued grandparent, return <code>0</code>.

A grandparent of a node is the parent of its parent if it exists.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/even1-tree.jpg" style="width: 504px; height: 302px;" />
<pre>
Input: root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
Output: 18
Explanation: The red nodes are the nodes with even-value grandparent while the blue nodes are the even-value grandparents.
</pre>

Example 2:
<img alt="" src="https://assets.leetcode.com/uploads/2021/08/10/even2-tree.jpg" style="width: 64px; height: 65px;" />
<pre>
Input: root = [1]
Output: 0
</pre>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 104]</code>.</li>
	<li><code>1 &lt;= Node.val &lt;= 100</code></li>
</ul>

sumEvenGrandparent

Sum of Nodes with Even-Valued Grandparent

Tree

Depth-First Search

Breadth-First Search

Binary Tree

给你一棵二叉树，请你返回满足以下条件的所有节点的值之和：

<ul>
	<li>该节点的祖父节点的值为偶数。（一个节点的祖父节点是指该节点的父节点的父节点。）</li>
</ul>

如果不存在祖父节点值为偶数的节点，那么返回&nbsp;<code>0</code> 。

&nbsp;

示例：

<img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/01/10/1473_ex1.png" style="height: 214px; width: 350px;">

<pre>输入：root = [6,7,8,2,7,1,3,9,null,1,4,null,null,null,5]
输出：18
解释：图中红色节点的祖父节点的值为偶数，蓝色节点为这些红色节点的祖父节点。
</pre>

&nbsp;

提示：

<ul>
	<li>树中节点的数目在&nbsp;<code>1</code> 到&nbsp;<code>10^4</code>&nbsp;之间。</li>
	<li>每个节点的值在&nbsp;<code>1</code> 到&nbsp;<code>100</code> 之间。</li>
</ul>