# 1315. Sum of Nodes with Even-Valued Grandparent

<https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent>

## Description

Given the `root` 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 `0`.

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

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/08/10/even1-tree.jpg)

```
**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.
```

**Example 2:**

![](https://assets.leetcode.com/uploads/2021/08/10/even2-tree.jpg)

```
**Input:** root = [1]
**Output:** 0
```

**Constraints:**

* The number of nodes in the tree is in the range `[1, 104]`.
* `1 <= Node.val <= 100`

## ac

```java
```