LeetCode Binary Tree Paths

Description

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

   1
 /   \
2     3
 \
  5

All root-to-leaf paths are:

["1->2->5", "1->3"]

The original problem is here.

The original code is here.

My Solution

I solve this problem in C++, as below:

/*
*Binary Tree Paths 
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<vector>
#include<stdlib.h>
using namespace std;
/**
 * 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> result;
    vector<string> binaryTreePaths(TreeNode* root) {
        string str;
        TreePath(root, str);
        return result;
    }
    void TreePath(TreeNode* root, string str){
        if(root == NULL)
            return;
        stringstream ss;
        string val;
        ss<<root->val;
        ss>>val;
        ss.clear();
        if(root->left == NULL && root->right == NULL){
            if(str.size() == 0)
                str += val;
            else{
                str.push_back('-');
                str.push_back('>');
                str += val;
            }
            result.push_back(str);        
        }
        else{
            if(root->left != NULL){
                string str1 = str;
                if(str1.size() == 0)
                    str1 += val;
                else{
                    str1.push_back('-');
                    str1.push_back('>');
                    str1 += val;
                }
                TreePath(root->left, str1);
            }
            if(root->right != NULL){
                string str2 = str;
                if(str2.size() == 0)
                    str2 += val;
                else{
                    str2.push_back('-');
                    str2.push_back('>');
                    str2 += val;
                }
                TreePath(root->right, str2);
            }
        }     
    }
};

Note

To solve the problem, depth-first search was used.