<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:
    int numSimilarGroups(vector<string>& strs) {
        unordered_map<string, bool> visited;
        for (string s : strs) {
            visited[s] = false;
        }
        
        vector<vector<string>> groups;
        
        for (int i = 0; i < strs.size(); i++) { 
            if (visited[strs[i]])
                continue;
            
            queue<string> queue;
            queue.push(strs[i]);
            visited[strs[0]] = true;
            vector<string> similarWords;
            
            while (!queue.empty()) {
                string word = queue.front();
                queue.pop();
                
                for (int j = 0; j < strs.size(); j++) {
                    if (visited[strs[j]])
                        continue;

                    if(areWordsSimilar(word, strs[j])) {
                        queue.push(strs[j]);
                        visited[strs[j]] = true;
                    }
                }
                
                similarWords.push_back(word);
            }
            
            groups.push_back(similarWords);
        }
        
        return groups.size(); 
    }
    
    bool areWordsSimilar(string one, string two) {
        if (one.size() != two.size())
            return false;
        
        char a = 'a';
        char b = 'b';
        int count = 0;
        
        for (int i = 0; i < one.size(); i++) {
            if (one.at(i) == two.at(i))
                continue;
            
            count++;
            if (count > 2)
                return false;
            
            if (count == 1) {
                a = one.at(i);
                b = two.at(i);
            }
            if (count == 2) {
                if (a != two.at(i) || b != one.at(i))
                    return false;
            }
        }
        
        return true;
    }
    
};
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