leetcode_c++:树:Sum Root to Leaf Numbers(129)

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.

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class Solution {private:    int sum;    void dfs(TreeNode *cur, int num) {        num = num * 10 + cur->val;        if (!cur->left && !cur->right) {            sum += num;            return;        }        if (cur->left)            dfs(cur->left, num);        if (cur->right)            dfs(cur->right, num);    }public:    int sumNumbers(TreeNode *root) {        if (!root)            return 0;        sum = 0;        dfs(root, 0);        return sum;    }};