<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) {
        int n = strs.size();
        int ans = 0;
        string prefix = "";
        for(int length = 1; length < 200; length++) {
            bool flag = true;
            string substr = "";
            for(int i=0; i<n;i++) {
                if (strs[i].size() < length) {
                    flag = false;break;
                }
                if (substr == "") {
                    substr = strs[i].substr(0, length);
                } else {
                    if(substr != strs[i].substr(0, length)) {
                        flag = false;
                        break;
                    }
                }
            }
            
            if (flag) {
                ans = length;
                prefix = substr;
                cout << substr << "\n";
            }
        }
        return prefix;
    }
};
17200