<blockquote>Note: This is a companion problem to the <a href="https://leetcode.com/discuss/interview-question/system-design/" target="_blank">System Design</a> problem: <a href="https://leetcode.com/discuss/interview-question/124658/Design-a-URL-Shortener-(-TinyURL-)-System/" target="_blank">Design TinyURL</a>.</blockquote>

<p>TinyURL is a URL shortening service where you enter a URL such as <code>https://leetcode.com/problems/design-tinyurl</code> and it returns a short URL such as <code>http://tinyurl.com/4e9iAk</code>. Design a class to encode a URL and decode a tiny URL.</p>

<p>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.</p>

<p>Implement the <code>Solution</code> class:</p>

<ul>
	<li><code>Solution()</code> Initializes the object of the system.</li>
	<li><code>String encode(String longUrl)</code> Returns a tiny URL for the given <code>longUrl</code>.</li>
	<li><code>String decode(String shortUrl)</code> Returns the original long URL for the given <code>shortUrl</code>. It is guaranteed that the given <code>shortUrl</code> was encoded by the same object.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> url = &quot;https://leetcode.com/problems/design-tinyurl&quot;
<strong>Output:</strong> &quot;https://leetcode.com/problems/design-tinyurl&quot;

<strong>Explanation:</strong>
Solution obj = new Solution();
string tiny = obj.encode(url); // returns the encoded tiny url.
string ans = obj.decode(tiny); // returns the original url after decoding it.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= url.length &lt;= 10<sup>4</sup></code></li>
	<li><code>url</code> is guranteed to be a valid URL.</li>
</ul>

class Solution {
public:
    string getCode() const {
        constexpr std::string_view chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
        std::stringstream str;
        for(auto i = 0; i < 6; ++i) {
            str << chars[rand() % chars.size()];
        }
        return "http://tinyurl.com/" + str.str();
    }
    
    string encode(const string& longUrl) {
        if(const auto ucfound = urltocode.find(longUrl); ucfound != urltocode.cend()) {
            return ucfound->second;
        }

        auto code = std::string{};
        do {
            code = getCode();
        }
        while(codetourl.count(code) != 0);

        urltocode.insert(std::make_pair(longUrl, code));
        codetourl.insert(std::make_pair(code, longUrl));
        return code;
    }

    string decode(const string& shortUrl) const {
        return codetourl.find(shortUrl)->second;
    }

private:
    unordered_map<string, string> urltocode;
    unordered_map<string, string> codetourl;
};
11100