LeetCode-Sum Root to Leaf Numbers

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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.

Solution:

Code:

<span style="font-size:14px;">/** * 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 helper(int &sum, TreeNode *root, int tempSum) {        if (!root->left && !root->right) {            sum += tempSum*10+root->val;            return;        }        if (root->left) helper(sum, root->left, tempSum*10+root->val);        if (root->right) helper(sum, root->right, tempSum*10+root->val);    }        int sumNumbers(TreeNode *root) {        if (root == NULL) return 0;        int sum = 0;        helper(sum, root, 0);        return sum;    }};</span>

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