535. Encode and Decode 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.

class Codec:

def __init__(self):
self.urls = []

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

:type longUrl: str
:rtype: str
"""
self.urls.append(longUrl)
return "http://tinyurl.com/" + str(len(self.urls)-1)

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

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

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

另解：

import random, string
class Codec:
alphabet = string.ascii_letters + string.digits
def __init__(self):
self.url2code = {}
self.code2url = {}

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

:type longUrl: str
:rtype: str
"""
while longUrl not in self.url2code:
code = ''.join(random.choice(Codec.alphabet) for _ in range(6))
if code not in self.code2url:
self.url2code[longUrl] = code
self.code2url[code] = longUrl
return "http://tinyurl.com/" + self.url2code[longUrl]

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

:type shortUrl: str
:rtype: str
"""
return self.code2url[shortUrl[-6:]]