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

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1315. Sum of Nodes with Even-Valued Grandparent (Medium)

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:

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:

Input: root = [1]
Output: 0

 

Constraints:

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

Related Topics

[Tree] [Depth-First Search] [Breadth-First Search] [Binary Tree]

Hints

Hint 1

Traverse the tree keeping the parent and the grandparent.

Hint 2

If the grandparent of the current node is even-valued, add the value of this node to the answer.