Skip to content

1315. Sum of Nodes with Even-Valued Grandparent

Difficulty Topics

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:

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

Solution

sum-of-nodes-with-even-valued-grandparent.py
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def dfs(self, current, parent, grandparent):
        if not current: return 0
        res = 0
        if grandparent and grandparent.val % 2 == 0:
            res += current.val

        return res + self.dfs(current.left, current, parent) + self.dfs(current.right, current, parent)

    def sumEvenGrandparent(self, root: TreeNode) -> int:
        return self.dfs(root, None, None)