Binary Tree Paths

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<string> binaryTreePaths(TreeNode* root) {
13         vector<string> result;
14         if(!root) return result;
15         
16         dfs(root, result, "");
17         return result;
18     }
19     void dfs(TreeNode* root, vector<string>& result, string temp){
20         if(!root) return;
21         
22         temp = temp + std::to_string(root->val);
23         if(root->left) dfs(root->left, result, temp + "->");
24         if(root->right) dfs(root->right, result, temp + "->");
25         if(!root->left && !root->right) result.push_back(temp);
26     }
27     /*string i2a(int val){
28         if(val == 0) return "0";
29         
30         string result;
31         if(val < 0){
32             result += "-";
33             val = -val;
34         }
35         while(val){
36             result += val % 10 + ‘0‘;
37             val /= 10;
38         }
39         int i = 0;
40         if(result[0] = ‘-‘) i = 1;
41         for(int j = result.length() - 1; i <= j; i++, j--){
42             swap(result[i], result[j]);
43         }
44         return result;
45     }*/
46 };