<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) {

        // find the smallest
        string small;
        string big;

        if (str1.length() > str2.length()) {
            small = str2;
            big = str1;
        } else {
            small = str1;
            big = str2;
        }

        for (int i = small.length(); i > 0; i--) {
            if (small.length() % (i) != 0) {
                continue;
            }
            string candidate = small.substr(0, i);

            int count = small.length() / i;

            string testStr = "";
             for (int x = 0; x < count; x++) {
                testStr += candidate;
            }

            if (testStr == small) // candidate divides small
            {
                // check if it also divides big
                if (big.length() % i == 0) {
                    int bigCount = big.length() / i;

                    string testStr2 = "";

                    for (int y = 0; y < bigCount; y++) {
                        testStr2 += candidate;
                    }

                    if(testStr2 == big){
                        return candidate;
                    }
                }
            }
        }

        return "";
    }
};
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