- Sum of Nodes with Even-Valued Grandparent
Medium
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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
解法1：
/**
* 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 sumEvenGrandparent(TreeNode* root) {
traversal(root, NULL, NULL);
return sum;
}
private:
int sum = 0;
void traversal(TreeNode *root, TreeNode *father, TreeNode *grandFather) {
if (!root) return;
if (root && grandFather && !(grandFather->val & 0x1)) {
sum += root->val;
}
traversal(root->left, root, father);
traversal(root->right, root, father);
}
};
