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535. Encode and Decode TinyURL.py
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535. Encode and Decode TinyURL.py
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# 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.
#
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))
class Codec:
alphabet = string.ascii_letters + '0123456789'
def __init__(self):
self.url2code = {}
self.code2url = {}
def encode(self, longUrl):
while longUrl not in self.url2code:
code = ''.join(random.choice(Codec.alphabet) for _ in range(6))
if code not in self.code2url:
self.code2url[code] = longUrl
self.url2code[longUrl] = code
return 'http://tinyurl.com/' + self.url2code[longUrl]
def decode(self, shortUrl):
return self.code2url[shortUrl[-6:]]