leetcode随驾刷题记录 1315祖父节点值为偶数的节点和

思路：先遍历二叉树，为偶数的则向下找两个层加起来

class Solution {
public:

    int an = 0;
    int sumEvenGrandparent(TreeNode* root) {
        bianli(root);
        return an;
    }
    void findSon(int level, TreeNode *node){
        if(level == 2){
            an += node->val;
        //    cout << an << endl;
            return;
        }else{
            if(node->left != nullptr){
                findSon(level+1, node->left);
            }
            if(node->right != nullptr){
                findSon(level+1, node->right);
            }
        }
    }
    void bianli(TreeNode *node){
        if(node->val % 2 == 0){
            findSon(0, node);
        }
        if(node->left != nullptr){
            bianli(node->left);
        }
        if(node->right != nullptr){
            bianli(node->right);
        }
        
    }
};