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.

基本题：

    int sumNumbers(TreeNode* root){    int total=0;calSum(root,total,0);return total;}void calSum(TreeNode* root,int& tot,int cur){if (!root)return;cur=cur*10+root->val;if (!root->left&&!root->right){tot+=cur;return;}if(root->left)calSum(root->left,tot,cur);if(root->right)calSum(root->right,tot,cur);}