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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思路：典型dfs 深度搜索

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {    private:        int  m_sum;        vector
     
       m_vec;        int intVec2Int(vector
      
        nums)        {            int num = 0;            for(int i = 0; i < nums.size(); i++)            {                num = num * 10 + nums[i];            }            return num;        }        void dfs(TreeNode* root)        {            if(root == NULL)                return;            m_vec.push_back(root->val);            if(root->left == NULL && root->right == NULL)            {                m_sum += intVec2Int(m_vec);                m_vec.pop_back();                return;            }            if(root->left)                dfs(root->left);            if(root->right)                dfs(root->right);            m_vec.pop_back();        }    public:        int sumNumbers(TreeNode *root)        {            m_vec.clear();            m_sum = 0;            dfs(root);            return m_sum;        }};