/**

  * 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:

     vector<string> vs_;

     void dfs(TreeNode* root, string s){

         if(!root) return;

         if(!root->left && !root->right){

            char t[] = "";

            sprintf(t, "->%d", root->val);

            vs_.push_back(s + string(t));

            return;

         }

         else{

            char t[] = "";

            sprintf(t, "->%d", root->val);

            dfs(root->left, s + string(t));

            dfs(root->right, s + string(t));

         }

     }

     vector<string> binaryTreePaths(TreeNode* root) {

         vs_.clear();

         if(!root) return vs_;

         char t[] = "";

         sprintf(t, "%d", root->val);

         string s(t);

         if(!root->left && !root->right){

             vs_.push_back(s);

             return vs_;

         }

         dfs(root->left, s);

         dfs(root->right, s);

         return vs_;

     }

 };