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.
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.
Constraints:
- The number of nodes in the tree is between
1and10^4. - The value of nodes is between
1and100.
Solution: Recursion
Time complexity: O(n)
Space complexity: O(n)
C++
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// Author: Huahua class Solution { public: int sumEvenGrandparent(TreeNode* root, int p = 1, int gp = 1) { if (!root) return 0; return sumEvenGrandparent(root->left, root->val, p) + sumEvenGrandparent(root->right, root->val, p) + (gp & 1 ? 0 : root->val); } }; |
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