1315. Sum of Nodes with Even-Valued Grandparent - medium
문제
Given a binary tree, return the sum of values of nodes with even-valued grandparent. (A grandparent of a node is the parent of its parent, if it exists.)
If there are no nodes with an even-valued grandparent, return 0.
제한사항
- The number of nodes in the tree is between 1 and 10^4.
- The value of nodes is between 1 and 100.
입출력 예
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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.
풀이
- Tree, BFS
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/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int sumEvenGrandparent(TreeNode* root) {
int sum = 0;
queue<TreeNode*> q;
q.push(root);
while(!q.empty()){
auto node = q.front();
q.pop();
if(node->val % 2 == 0){
if(node->left){
if(node->left->left){
sum += node->left->left->val;
}
if(node->left->right){
sum += node->left->right->val;
}
}
if(node->right){
if(node->right->left){
sum += node->right->left->val;
}
if(node->right->right){
sum += node->right->right->val;
}
}
}
if(node->left)
q.push(node->left);
if(node->right)
q.push(node->right);
}
return sum;
}
};