<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>

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        if (strs.size() == 1) return strs[0];
        int len = strs.size();
        string s1 = strs[len-1];
        string s2 = strs[len-2];

        if (s1.length() == 0 || s2.length() == 0) return "";

        string substr = "";
        string subbie = "";
        int i=0;
        int c1_counter = 0;
        int c2_counter = 0;
        
        char c1 = s1[c1_counter];
        char c2 = s2[c2_counter];
        while (c1 == c2) {
            subbie.push_back(c1);
            c1_counter++;
            c2_counter++;
            if (c1_counter == s1.length() || c2_counter == s2.length()) break;

            c1 = s1[c1_counter];
            c2 = s2[c2_counter];
        }
        if (subbie == "") return subbie;

        substr = subbie;
        strs.pop_back();
        strs.pop_back();
        strs.push_back(substr);
        substr = longestCommonPrefix(strs);   

        return substr;
    }
};
13800