File System 


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#pragma once
#include<iostream>
#include<unordered_map>
#include<string>
#include<sstream>

using namespace std;

namespace airbnb
{
    struct TrieNode
    {
        TrieNode()
    {
        this->value = -1;
    }

    unordered_map<string, TrieNode*> children;
    int value;
    };

    class FileSystem
    {
    private:
        TrieNode *root;

        void deleteTrie(TrieNode *p) {
            for (auto& pchild : p->children) {
                deleteTrie(pchild.second);
            }
            delete p;
        }

    public:
        FileSystem()
        {
            root = new TrieNode();
        }

        ~FileSystem()
        {
            deleteTrie(root);
        }

        void Create(string path, int value)
        {
            TrieNode *p = root;

            string dir = "";
            string logStr = "";
            stringstream sspath(path);
            while (getline(sspath, dir, '/')) {
                if (dir == "") {
                    continue;
                }

                logStr.append("/" + dir);
                if (p->children.find(dir) == p->children.end()) {
                    break;
                }
                p = p->children[dir];
            }

            if (!sspath.eof()) {
                cout << "Create: Error because " << logStr << " does not exist" << endl;
                return;
            }

            p->children[dir] = new TrieNode();
            p->children[dir]->value = value;

            cout << "create path: " << logStr << " successfully" << endl;
        }

        int Get(string path)
        {
            TrieNode* p = root;

            stringstream sspath(path);
            string dir = "";
            while (getline(sspath, dir, '/')) {
                if (dir == "") {
                    continue;
                }

                if (p->children.find(dir) == p->children.end()) {
                    cout << "Get: Error. Path: " << path << " does not exist" << endl;
                    return - 1;
                }
                p = p->children[dir];
            }

            cout << "Get value: " << p->value << endl;
            return p->value;
        }

        void DoTest()
        {
            FileSystem fs;
            fs.Create("/a", 1);
            fs.Get("/a");
            fs.Create("/a/b", 2);
            fs.Create("/c/d", 1);
            fs.Get("/c");
        }
    };
}

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