<p>For two strings <code>s</code> and <code>t</code>, we say &quot;<code>t</code> divides <code>s</code>&quot; if and only if <code>s = t + t + t + ... + t + t</code> (i.e., <code>t</code> is concatenated with itself one or more times).</p>

<p>Given two strings <code>str1</code> and <code>str2</code>, return <em>the largest string </em><code>x</code><em> such that </em><code>x</code><em> divides both </em><code>str1</code><em> and </em><code>str2</code>.</p>

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

<pre>
<strong>Input:</strong> str1 = &quot;ABCABC&quot;, str2 = &quot;ABC&quot;
<strong>Output:</strong> &quot;ABC&quot;
</pre>

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

<pre>
<strong>Input:</strong> str1 = &quot;ABABAB&quot;, str2 = &quot;ABAB&quot;
<strong>Output:</strong> &quot;AB&quot;
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> str1 = &quot;LEET&quot;, str2 = &quot;CODE&quot;
<strong>Output:</strong> &quot;&quot;
</pre>

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

<ul>
	<li><code>1 &lt;= str1.length, str2.length &lt;= 1000</code></li>
	<li><code>str1</code> and <code>str2</code> consist of English uppercase letters.</li>
</ul>

class Solution {
public:
    bool checkIfDivides(string s1, string s2){
        if(s2.size()%s1.size()!= 0)
            return false;
        int times = s2.size() / s1.size();
        string newS = "";
        for(int i = 0; i < times; i++){
            newS += s1;
        }
        return newS == s2;
    }
    string gcdOfStrings(string str1, string str2) {
        if(str1.size()>str2.size()){
            auto temp = str1;
            str1 = str2;
            str2 = temp;
        }
        string s = str1;
        for(int i = str1.size()-1; i>=0; i--){
           
            if(checkIfDivides(s,str1) && checkIfDivides(s,str2))
                return s;
            s = str1.substr(0,i);
        }
        return "";
    }
};
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