<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:
    string gcdOfStrings(string str1, string str2) {
        int n=str1.size();
        int m=str2.size();
        int minn=min(n,m);
        string minstr="";
        string nonmin=str1;
        if(minn==n) {minstr=str1;
        nonmin=str2;}
        else minstr=str2;
        string ans="";
         for (int i = 1; i <= minn; i++) {
            // Only check if 'i' is a divisor of both n and m
            if (n % i != 0 || m % i != 0) continue;
            
            string check = minstr.substr(0, i);
            
            // Check if both str1 and str2 are made up of this substring
            bool isDivisibleStr1 = true, isDivisibleStr2 = true;
            
            // Check str1
            for (int j = 0; j < n; j += i) {
                if (str1.substr(j, i) != check) {
                    isDivisibleStr1 = false;
                    break;
                }
            }
            
            // Check str2
            for (int j = 0; j < m; j += i) {
                if (str2.substr(j, i) != check) {
                    isDivisibleStr2 = false;
                    break;
                }
            }
            
            // If both strings are divisible by this prefix, update the answer
            if (isDivisibleStr1 && isDivisibleStr2) {
                ans = check;
            }
        }
        return ans;
    }
};
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