Sum Root to Leaf Numbers

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 binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
    void sumNumbersInt(TreeNode *root, string path, int &pathSum)
    {
        if (!root)
            return;      
        if (!root->left && !root->right)
        {
           path+=to_string(root->val);
           pathSum+=atoi(path.c_str());
        }
        string currentPath = path + to_string(root->val);
        sumNumbersInt(root->left, currentPath, pathSum);
        sumNumbersInt(root->right, currentPath, pathSum);
    }
public:
    int sumNumbers(TreeNode *root) 
    {
        int pathSum=0;
        string path;
        if (!root)
            return 0;
        if (!root->left && !root->right)
            return root->val;
        sumNumbersInt(root, path, pathSum);
        return pathSum;
    }
};