<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 checkDivisible(string s, string t) {
        int m = s.length();
        int n = t.length();
        int q = m/n;
        string temp = "";
        for(int i = 0; i < q; i++) {
            temp += t;
        }
        return (s == temp);
    }

    string gcdOfStrings(string str1, string str2) {
        if (str1[0] != str2[0]) {
            return "";
        }

        int m = str1.length();
        int n = str2.length();
        int max_len = gcd(m,n);
        string ans = "";
        for(int i = 1; i <= max_len; i++) {
            if ((m % i == 0) && (n% i == 0)) {
                string t = str1.substr(0,i);
                if (checkDivisible(str1, t) && checkDivisible(str2, t)) {
                    ans = t;
                }
            }
            else {
                continue;
            }
        }
        return ans;
    }
};
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