Leetcode 535 encryption and decryption of tinyurl [map] the leetcode road of heroding

Their thinking ：
direct map Storage url, Then use a random string +URL Serial number instead of return , As an encrypted string , Decrypt and directly obtain the sequence number to return the corresponding value that will do , The code is as follows ：

class Solution {
    
private:
    int id = 0;
    unordered_map<int, string> mp;
public:

    // Encodes a URL to a shortened URL.
    string encode(string longUrl) {
    
        mp[id] = longUrl;
        return "noway.com/" + to_string(id);
        id ++;
    }

    // Decodes a shortened URL to its original URL.
    string decode(string shortUrl) {
    
        int i = stoi(shortUrl.substr(10, shortUrl.size() - 10));
        return mp[i];
    }
};

// Your Solution object will be instantiated and called as such:
// Solution solution;
// solution.decode(solution.encode(url));