<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();

        string minLenStr = strs[ 0 ];
        for( int i = 1; i < n; i++ ) {
            if( strs[ i ].size() < minLenStr.size() ) {
                minLenStr = strs[ i ];
            }
        }

        // Now create a hashMap of all the windows of the word with minimum length
        unordered_map< string, int > numWordsStartingWith;
        for( int i = 0; i < minLenStr.size(); i++ ) {
            numWordsStartingWith.insert( { minLenStr.substr( 0, i+1 ), 0} );
        }

        for( const auto& str : strs ) {
            for( int i = 0; i < minLenStr.size(); i++ ) {
                string prefix = str.substr( 0, i+1 );
                if( numWordsStartingWith.find( prefix ) == numWordsStartingWith.end() ) {
                    continue;
                }
                numWordsStartingWith[ prefix ]++;
            }
        }

        string result;
        for( const auto& [ prefix, numWords ] : numWordsStartingWith ) {
            if( numWords == n ) {
                result = ( prefix.size() > result.size() ) ? prefix : result;
            }
        }

        return result;
    }
};
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