<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 {
private:
    string lcp(vector<string>& strs, int begin, int end) {
        if (end == begin + 1) {
            return strs[begin];
        }

        int mid = (begin + end) / 2;
        string lcpLeft = lcp(strs, begin, mid);
        string lcpRight = lcp(strs, mid, end);

        int minLen = min(lcpLeft.size(), lcpRight.size());
        int idx;
        for (idx = 0; idx < minLen; idx++) {
            if (lcpLeft[idx] != lcpRight[idx]) {
                break;
            }
        }

        return lcpLeft.substr(0, idx);
    }
public:
    string longestCommonPrefix(vector<string>& strs) {
        return lcp(strs, 0, strs.size());
    }
};
13500