leetCode(36):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 a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    void sumNumber(TreeNode* root, int sum,int& result)     {    if (root == NULL) return;//直接返回        sum = sum * 10 + root->val;        if (root->left == NULL && root->right == NULL)     {//相加求和返回    result += sum;    return;    }        sumNumber(root->left, sum,result);    sumNumber(root->right, sum,result);    }    int sumNumbers(TreeNode* root) {        int result = 0;sumNumber(root, 0, result);    return result;    }};