1315. Sum of Nodes with Even-Valued Grandparent

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1315. 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:

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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:

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Input: root = [1]
Output: 0

Constraints:

  • The number of nodes in the tree is in the range [1, 10^4].
  • 1 <= Node.val <= 100

Hints/Notes

  • N/A

Solution

Language: C++

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
class Solution {
public:
    int res = 0;

    int sumEvenGrandparent(TreeNode* root) {
        traverse(root);
        return res;
    }

    void traverse(TreeNode* root) {
        if (!root) {
            return;
        }
        if (root->val % 2 == 0) {
            if (root->left) {
                res += root->left->left ? root->left->left->val : 0;
                res += root->left->right ? root->left->right->val : 0;
            }

            if (root->right) {
                res += root->right->left ? root->right->left->val : 0;
                res += root->right->right ? root->right->right->val : 0;
            }
        }

        traverse(root->left);
        traverse(root->right);
    }
};