232 · 短网址

news2024/9/25 17:17:55

链接：LintCode 炼码

题解：

class TinyUrl {
public:
    /*
     * @param url: a long url
     * @return: a short url starts with http://tiny.url/
     */
    string longToShort(string &url) {
        // write your code here
        std::string shorturl = generate_shorturl(url);
        while (url2short_.find(shorturl) != url2short_.end()) {
            shorturl = generate_shorturl(url);
        }
        shorturl = "http://tiny.url/" + shorturl;
        short2url_[shorturl] = url;
        url2short_[url] = shorturl;
        return shorturl;
    }

    /*
     * @param url: a short url starts with http://tiny.url/
     * @return: a long url
     */
    string shortToLong(string &url) {
        // write your code here
        auto ite = short2url_.find(url);
        if (ite == short2url_.end()) {
            return "";
        }
        return ite->second;
    }
private:
    std::string generate_shorturl(const std::string& url) {
        static std::string base = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        std::string result;
        result.resize(6);
        for (int i = 0; i < 6; ++i) {
            result[i] = base[random()%base.size()];
        }
        return result;
    }
private:
    std::unordered_map<std::string, std::string> url2short_;
    std::unordered_map<std::string, std::string> short2url_;
};