[Leetcode 129, Medium] Sum Root to Leaf Number

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Problem:

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.

Analysis:

Solutions:

C++:

    int ArrayToNumber(const vector<int>& array)    {        int size = array.size();        int value = 0;        for(int i = 0; i < size; ++i) {            value *= 10;            value += array[i];        }        return value;    }    int sumNumbers(TreeNode* root) {        if(root == NULL)            return 0;                int sum = 0;        TreeNode *p_cur = root;        TreeNode *p_visited = NULL;        stack<TreeNode *> node_stack;        vector<int> array_number;        while(p_cur || !node_stack.empty()) {            if(p_cur) {                node_stack.push(p_cur);                array_number.push_back(p_cur->val);                p_cur = p_cur->left;            } else {                p_cur = node_stack.top();                if(p_cur->right == NULL || p_cur->right == p_visited) {                    if(p_cur->right == NULL && p_cur->left == NULL)                        sum += ArrayToNumber(array_number);                    p_visited = p_cur;                    node_stack.pop();                    array_number.erase(array_number.end() - 1);                    p_cur = NULL;                } else                    p_cur = p_cur->right;            }        }                return sum;    }

Java:

Python:

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