Sum Root to Leaf Numbers
Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent
a number.
An example is the root-to-leaf path 1->2->3 which represents the number 123.
Find the total sum of all root-to-leaf numbers.
For example,
1 / 2 3
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Return the sum = 12 + 13 = 25.
递归，每个节点的值都是当前节点*10+右节点 + 当前节点*10+左节点。
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int sumNumbers(TreeNode *root) {
return dfs(root, 0);
}
private:
int dfs(TreeNode *root, int sum){
if(!root) return 0;
if(!root->left && !root->right) {
return sum*10 + root->val;
}
return dfs(root->left, sum*10 + root->val) +
dfs(root->right, sum*10 + root->val);
}
};
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