[Leetcode]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

.

/**
* 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:
void dfs(TreeNode* root,int& sum,int path){
if(!root)return;
if(!root->left&&!root->right){ //find one path
sum += path*10+root->val;
return;
}
dfs(root->left,sum,path*10+root->val);
dfs(root->right,sum,path*10+root->val);
}
int sumNumbers(TreeNode* root) {
int sum = 0;
dfs(root,sum,0);
return sum;
}
};