<p>Given an array of strings <code>strs</code>, return <em>the length of the <strong>longest uncommon subsequence</strong> between them</em>. If the longest uncommon subsequence does not exist, return <code>-1</code>.</p>

<p>An <strong>uncommon subsequence</strong> between an array of strings is a string that is a <strong>subsequence of one string but not the others</strong>.</p>

<p>A <strong>subsequence</strong> of a string <code>s</code> is a string that can be obtained after deleting any number of characters from <code>s</code>.</p>

<ul>
	<li>For example, <code>&quot;abc&quot;</code> is a subsequence of <code>&quot;aebdc&quot;</code> because you can delete the underlined characters in <code>&quot;a<u>e</u>b<u>d</u>c&quot;</code> to get <code>&quot;abc&quot;</code>. Other subsequences of <code>&quot;aebdc&quot;</code> include <code>&quot;aebdc&quot;</code>, <code>&quot;aeb&quot;</code>, and <code>&quot;&quot;</code> (empty string).</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> strs = ["aba","cdc","eae"]
<strong>Output:</strong> 3
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> strs = ["aaa","aaa","aa"]
<strong>Output:</strong> -1
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>2 &lt;= strs.length &lt;= 50</code></li>
	<li><code>1 &lt;= strs[i].length &lt;= 10</code></li>
	<li><code>strs[i]</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    // Helper function to check if `sub` is a subsequence of `str`
    bool isSubsequence(const string& sub, const string& str) {
        int i = 0, j = 0;
        while (i < sub.size() && j < str.size()) 
        {
            if (sub[i] == str[j]) i++;
            j++;
        }
        return i == sub.size();
    }

    int findLUSlength(vector<string>& strs) 
    {
        int n = strs.size();
        int maxLen = -1;
        unordered_set<string> checked;

        for (int i = 0; i < n; ++i) 
        {
            queue<string> q;
            q.push(strs[i]);
            while (!q.empty()) 
            {
                string current = q.front(); q.pop();

                if (checked.count(current)) continue;
                checked.insert(current);

                bool isUncommon = true;
                for (int j = i + 1; j < n; ++j) 
                {
                    if (isSubsequence(current, strs[j])) 
                    {
                        isUncommon = false;
                        break;
                    }
                }

                if (isUncommon) 
                {
                    maxLen = max(maxLen, (int)current.length());
                }

                // Generate all subsequences by deleting one character
                for (int k = 0; k < current.size(); ++k) 
                {
                    string next = current.substr(0, k) + current.substr(k + 1);
                    if (!checked.count(next)) 
                    {
                        q.push(next);
                    }
                }
            }
        }

        return maxLen;
    }

};
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