[LeetCode] 535. Encode and Decode TinyURL 编码和解码短网址

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.

Python:

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class Codec:     def __init__(self):         self.__random_length = 6         self.__tiny_url = "http://tinyurl.com/"         self.__alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"         self.__lookup = {}       def encode(self, longUrl):         """Encodes a URL to a shortened URL.                   :type longUrl: str         :rtype: str         """         def getRand():             rand = []             for _ in xrange(self.__random_length):                 rand += self.__alphabet[random.randint(0, len(self.__alphabet)-1)]             return "".join(rand)                   key = getRand()         while key in self.__lookup:             key = getRand()         self.__lookup[key] = longUrl         return self.__tiny_url + key       def decode(self, shortUrl):         """Decodes a shortened URL to its original URL.                   :type shortUrl: str         :rtype: str         """         return self.__lookup[shortUrl[len(self.__tiny_url):]]

 Python：Using sha256

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from hashlib import sha256   class Codec:       def __init__(self):         self._cache = {}         self.url = 'http://tinyurl.com/'       def encode(self, long_url):         """Encodes a URL to a shortened URL.         :type long_url: str         :rtype: str         """         key = sha256(long_url.encode()).hexdigest()[:6]         self._cache[key] = long_url         return self.url + key       def decode(self, short_url):         """Decodes a shortened URL to its original URL.         :type short_url: str         :rtype: str         """         key = short_url.replace(self.url, '')         return self._cache[key]

C++:

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class Solution { public:     Solution() : gen_((random_device())()) {     }       // Encodes a URL to a shortened URL.     string encode(string longUrl) {         string key = getRand();         while (lookup_.count(key)) {             key = getRand();         }         lookup_[key] = longUrl;         return "http://tinyurl.com/" + key;     }       // Decodes a shortened URL to its original URL.     string decode(string shortUrl) {         return lookup_[shortUrl.substr(tiny_url.length())];     }   private:     string getRand() {         string random;         for (int i = 0; i < random_length; ++i) {             random += alphabet_[uniform_int_distribution<int>{0, alphabet_.length() - 1}(gen_)];         }         return random;     }       const int random_length = 6;     const string tiny_url = "http://tinyurl.com/";     const string alphabet_ = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";     default_random_engine gen_;     unordered_map<string, string> lookup_; };

　　

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[LeetCode] 534. Design TinyURL 设计短网址

 

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