Encode and Decode TinyURL

最新推荐文章于 2022-04-23 22:33:21 发布

转载最新推荐文章于 2022-04-23 22:33:21 发布 · 250 阅读

系统设计专栏收录该内容

7 篇文章

订阅专栏

本文介绍了一种URL缩短服务的设计方案，通过TinyURL服务将长网址转换为短网址，并详细阐述了编码和解码的算法流程。该服务使用随机字符串确保短网址的唯一性，并能正确解析回原始长网址。

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 Solution {
public:
    
    Solution() {
        dict = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        short2long.clear();
        long2short.clear();
        srand(time(NULL));
    }
    
    // Encodes a URL to a shortened URL.
    string encode(string longUrl) {
        if(long2short.count(longUrl))
        {
            return "http://tinyurl.com/"+long2short[longUrl];
        }
        int idx = 0;
        string randStr;
        for(int i=0; i<6; i++) randStr.push_back(dict[rand()%62]);
        while(short2long.count(randStr))
        {
            randStr[idx] = dict[rand()%62];
            idx = (idx+1)%6;
        }
        long2short[longUrl] = randStr;
        short2long[randStr] = longUrl;
        return "http://tinyurl.com/"+long2short[longUrl];
    }

    // Decodes a shortened URL to its original URL.
    string decode(string shortUrl) {
        string randStr = shortUrl.substr(shortUrl.find_last_of("/") + 1);
        return short2long.count(randStr) ? short2long[randStr] : shortUrl;
    }
    
private:
    unordered_map<string, string> short2long, long2short;
    string dict;
};

// Your Solution object will be instantiated and called as such:
// Solution solution;
// solution.decode(solution.encode(url));