<p>Write a function to find the longest common prefix string amongst an array of strings.</p>

<p>If there is no common prefix, return an empty string <code>&quot;&quot;</code>.</p>

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

<pre>
<strong>Input:</strong> strs = [&quot;flower&quot;,&quot;flow&quot;,&quot;flight&quot;]
<strong>Output:</strong> &quot;fl&quot;
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> strs = [&quot;dog&quot;,&quot;racecar&quot;,&quot;car&quot;]
<strong>Output:</strong> &quot;&quot;
<strong>Explanation:</strong> There is no common prefix among the input strings.
</pre>

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

<ul>
	<li><code>1 &lt;= strs.length &lt;= 200</code></li>
	<li><code>0 &lt;= strs[i].length &lt;= 200</code></li>
	<li><code>strs[i]</code> consists of only lowercase English letters.</li>
</ul>

#include <unordered_map>
#include <memory>

struct Trie
{
    string value;
    unordered_map<string, std::shared_ptr<Trie>> children;
    Trie(string value) : value(value) { }

    std::shared_ptr<Trie> insert (string value)
    {
        auto node = children.find(value);
        if (node != children.end())
            return node->second;

        auto ref = std::make_shared<Trie>(Trie(value));
        children.insert({ value, ref });
        return children[value];
    }

    void insert (string& s, int offset, int length=-1)
    {
        if (length == -1)
            length = s.size();

        if (offset >= length) {
            insert("");
            return;
        }

        insert(s.substr(offset, 1))->insert(s, offset+1, length);
    }

    string getString() {
        if (children.size() == 1)
            return value + children.begin()->second->getString();
        return value;
    }
};

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs)
    {
        Trie root("");
        for (string& value : strs)
            root.insert(value, 0);
        return root.getString();
    }
};
16000