Encode and Decode TinyURL
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 ashttps://leetcode.com/problems/design-tinyurl
and it returns a short URL such ashttp://tinyurl.com/4e9iAk
.
Design theencode
anddecode
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.
分析
string.ascii_letters+string.digits 提供了可选的字符
''.join(random.choice(chars) for _ in range(6))得到了code
2个map code2url 和url2code
encode时候有个while longURL not in url2code 保证了code重复情况下依然可以create新code
class Codec:
alphabet = string.ascii_letters+string.digits
code_base = "http://tinyurl.com/"
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(self.alphabet) for _ in range(6))
if code not in self.code2url:
self.code2url[code] = longUrl
self.url2code[longUrl] = code
return self.code_base + code
def decode(self, shortUrl):
"""Decodes a shortened URL to its original URL.
:type shortUrl: str
:rtype: str
"""
return self.code2url[shortUrl[-6:]]
# Your Codec object will be instantiated and called as such:
# codec = Codec()
# codec.decode(codec.encode(url))
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