Most frequently asked interview question #14 with solution

Note: This is a companion problem to the System Design problem: Design TinyURL.

TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http://tinyurl.com/4e9iAk.
Design the encode and decode methods for the TinyURL service. There is no restriction on how your encode/decode algorithm should work. You just need to ensure that a URL can be encoded to a tiny URL and the tiny URL can be decoded to the original URL.

Solution in C++:

class Solution {
public:
    map<string, string> url;
   
    // Encodes a URL to a shortened URL.
    string encode(string longUrl) {
        static int count = 0;
        char *a = (char*)calloc(sizeof(char), 30);
        ++count;
        sprintf(a,"%s%d","https://tinyurl.com/",count);

        url.insert({a, longUrl});

        return a;
    }

    // Decodes a shortened URL to its original URL.
    string decode(string shortUrl) {

        auto temp = url.find(shortUrl);

        if(temp != url.end()){

            return temp->second;
        }
       
        return nullptr;
    }
};