<-M 129> Sum Root to Leaf Numbers
/**
* 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 sumNumbers(TreeNode* root) {
return dfs(root, 0);
}
private:
int dfs(TreeNode *root, int sum) {
if(root == nullptr)
return 0;
if(root->left == nullptr && root->right == nullptr)
return sum * 10 + root->val;
return dfs(root->left, sum * 10 + root->val) +
dfs(root->right, sum * 10 + root->val);
}
};