public class Codec {
    
    HashMap<String,String> map ;    //<LongUrl,ShortUrl>
    
    //constructor
    public Codec(){
        this.map = new HashMap<>();
    }

    // Encodes a URL to a shortened URL.
    public String encode(String longUrl) {
        
        //making a random number throuhg math.encoding eg: 53.15 and round it off 
        //after rounding it off change it into ascii character , it that character
        //exists in the HM add another random character to the stringbuilder 
        //untill it is not contained in the HM

        //use SB as operations in SB are in O(1) and in string is o(n)
        StringBuilder shortUrl = new StringBuilder();
        shortUrl.append((char)(Math.floor(Math.random()*100)));
        
        while(map.containsKey(shortUrl))
        shortUrl.append((char)(Math.floor(Math.random()*100)));

        map.put(shortUrl.toString(),longUrl);
        

        return shortUrl.toString();
    }

    // Decodes a shortened URL to its original URL.
    public String decode(String shortUrl) {
        String longUrl = map.get(shortUrl);

        return longUrl.toString();
    }
}

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.decode(codec.encode(url));