535. Encode and Decode TinyURL

Python

import random
from urllib.parse import urljoin
from string import ascii_letters, digits

class Codec:
    CHARS = ascii_letters + digits
    BASE_URL = 'https://tinyurl.com/'

    def __init__(self):
        self.mapper = dict()
        self.used = set()

    def _generate(self):
        return ''.join([random.choice(self.CHARS) for i in range(8)])

    def encode(self, longUrl: str) -> str:
        """Encodes a URL to a shortened URL.
        """
        cand = self._generate()
        while cand in self.used:
            cand = self._generate()

        url = urljoin(self.BASE_URL, cand)
        self.mapper[url] = longUrl
        self.used.add(cand)
        return url

    def decode(self, shortUrl: str) -> str:
        """Decodes a shortened URL to its original URL.
        """
        if shortUrl not in self.mapper:
            return
        return self.mapper[shortUrl]

# Your Codec object will be instantiated and called as such:
# codec = Codec()
# codec.decode(codec.encode(url))
Python​

Python
