129 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 {
public:
    int sumNumbers(TreeNode *root) {
        int res = 0;
        int sum=0;
        help(root, res, sum);
        return sum;
    }
    void help(TreeNode *root, int res, int &sum)
    {
        if (!root)
            return;
        res = res*10 + root->val;
        if (!root->left && !root->right)
        {
            sum+= res;
            return;
        }
        if (root->left)
        {
            help(root->left, res, sum);
        }
        if (root->right)
        {
            help(root->right,res,sum);
        }
    }
};

/**
 * 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) {
        int sum=0;
        if (!root)
            return 0;
        queue<TreeNode*> q;
        q.push(root);
        while(!q.empty())
        {
            TreeNode * tmp = q.front();
            q.pop();
            if (!tmp->left && !tmp->right)
            {
                sum+= tmp->val;
            }
            else
            {
                if (tmp->left)
                {
                    tmp->left->val += tmp->val*10;
                    q.push(tmp->left);
                }
                if (tmp->right)
                {
                    tmp->right->val += tmp->val*10;
                    q.push(tmp->right);
                }
            }
        }
        return sum;
    }
    
};