tiny_url.py

from collections import defaultdict
import random
import string

alphabet = string.ascii_letters + '0123456789'

class Codec:

    def __init__(self):
        self.urls = defaultdict(str)

    def encode(self, longUrl):
        """Encodes a URL to a shortened URL.

        :type longUrl: str
        :rtype: str
        """
        hash = ''.join(random.choices(alphabet, k=6))
        if hash in self.urls:
            return self.urls[hash]
        else:
            self.urls[hash] = longUrl
            return f"http://tinyurl.com/{hash}"

    def decode(self, shortUrl):
        """Decodes a shortened URL to its original URL.

        :type shortUrl: str
        :rtype: str
        """
        hash = shortUrl.split('/')[-1]
        return self.urls[hash]