<p>Two strings, <code>X</code> and <code>Y</code>, are considered similar if either they are identical or we can make them equivalent by swapping at most two letters (in distinct positions) within the string <code>X</code>.</p>

<p>For example, <code>&quot;tars&quot;</code>&nbsp;and <code>&quot;rats&quot;</code>&nbsp;are similar (swapping at positions <code>0</code> and <code>2</code>), and <code>&quot;rats&quot;</code> and <code>&quot;arts&quot;</code> are similar, but <code>&quot;star&quot;</code> is not similar to <code>&quot;tars&quot;</code>, <code>&quot;rats&quot;</code>, or <code>&quot;arts&quot;</code>.</p>

<p>Together, these form two connected groups by similarity: <code>{&quot;tars&quot;, &quot;rats&quot;, &quot;arts&quot;}</code> and <code>{&quot;star&quot;}</code>.&nbsp; Notice that <code>&quot;tars&quot;</code> and <code>&quot;arts&quot;</code> are in the same group even though they are not similar.&nbsp; Formally, each group is such that a word is in the group if and only if it is similar to at least one other word in the group.</p>

<p>We are given a list <code>strs</code> of strings where every string in <code>strs</code> is an anagram of every other string in <code>strs</code>. How many groups are there?</p>

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

<pre>
<strong>Input:</strong> strs = [&quot;tars&quot;,&quot;rats&quot;,&quot;arts&quot;,&quot;star&quot;]
<strong>Output:</strong> 2
</pre>

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

<pre>
<strong>Input:</strong> strs = [&quot;omv&quot;,&quot;ovm&quot;]
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= strs.length &lt;= 300</code></li>
	<li><code>1 &lt;= strs[i].length &lt;= 300</code></li>
	<li><code>strs[i]</code> consists of lowercase letters only.</li>
	<li>All words in <code>strs</code> have the same length and are anagrams of each other.</li>
</ul>

class Solution {
public:
    bool isSimilar(const string& a, const string& b) {
        if (a.size() != b.size())
            return false;

        unordered_set<char> uc;
        int violation_count = 0;
        for (int i = 0; i < a.size(); i++) {
            if (a[i] != b[i])
                uc.insert(a[i]), uc.insert(b[i]), violation_count++;

            if (uc.size() > 2 || violation_count > 2)
                return false;
        }

        return true;
    }

    int numSimilarGroups(const vector<string>& strs) {
        vector<int> v(strs.size(), 0);
        for (int i = 0; i < strs.size(); i++)
            v[i] = i;

        for (int i = 0; i < strs.size(); i++)
            for (int j = i + 1; j < strs.size(); j++)
                if (isSimilar(strs[i], strs[j])) {
                    const int b = v[i], c = v[j];
                    const int a = min(b, c);

                    for (int k = 0; k < strs.size(); k++) {
                        if (v[k] == b || v[k] == c) {
                            // cout << k << "." << v[k] << "." << a << ", ";
                            v[k] = a;
                        }
                    }

                    // cout << "\n";
                }

        // cout << '\n';
        // for(int i = 0; i < strs.size(); i++) {
        //     cout << v[i] << " : " << strs[i] << " : " << v[i] << '\n';
        // }

        unordered_set<int> um;
        for (const int& i : v)
            um.insert(i);

        return um.size();
    }
};
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