[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.

class Solution {
public:
    int sumNumbers(TreeNode *root) {
		// Start typing your C/C++ solution below
		// DO NOT write int main() function
		if(!root)return 0;
		int itermedia=0,sum=0;
		DFS(root,itermedia,sum);
		return sum;
	}
	void DFS(TreeNode *root, int& itermedia, int& sum){
		itermedia=itermedia*10+root->val;
		if(!root->left && !root->right){
			sum+=itermedia;
			itermedia/=10;
			return;
		}
		if(root->left)
			DFS(root->left,itermedia,sum);
		if(root->right)
			DFS(root->right,itermedia,sum);
		itermedia/=10;
	}
};