二叉树各分支的和

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 number123.

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:    void visitNode(TreeNode *root, int prevSum, int &sum)    {        if (root == NULL)        {            return;        }        if (root->left == NULL && root->right == NULL)        {            sum += 10*prevSum + root->val;            return;        }        if (root->left)        {            visitNode(root->left, 10*prevSum + root->val, sum);        }        if (root->right)        {            visitNode(root->right, 10*prevSum + root->val, sum);        }    }        int sumNumbers(TreeNode *root) {        int sum = 0;        visitNode(root, 0, sum);        return sum;    }};