<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:
    def similar(self, x, y):
        cnt = 0
        for i in range(len(x)):
            if x[i] != y[i]:
                cnt += 1
                if cnt > 2:
                    return False
        return True 

    def numSimilarGroups(self, A: List[str]) -> int:
        wordlen = len(A[0])
        A = set(A)
        divs = defaultdict(list)
        if wordlen > 6:
            for word in A:
                step = wordlen // 3
                for i in range(0, step * 3, step):
                    divs[word[i:i+step] + str(i)].append(word)
        else:
            divs['all'].extend(A)
        
        graph = defaultdict(set)
        for _list in divs.values():
            for i, a in enumerate(_list):
                for j, b in enumerate(_list[i+1:], i+1):
                    if self.similar(a, b):
                        graph[a].add(b)
                        graph[b].add(a)
        ans = 0 
        cc = set()
        for word in A:
            if word not in cc:
                queue = [word]
                while queue:
                    cur = queue.pop()
                    cc.add(cur)
                    for nx in graph[cur]:
                        if nx not in cc:
                            queue.append(nx)
                ans += 1
        return ans
17200