<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 numSimilarGroups(self, strs: List[str]) -> int:
        n, codes, lens = len(strs), [], []
        L = 2
        for i in range(n):
            l = len(strs[i])
            lens.append(l)
            codes.append([])
            for j in range(0, l, L):
                code = 0
                for k in range(j, min(l, j + L)):
                    code = code * 26 + ord(strs[i][k]) - ord('a')
                codes[i].append(code)

        def is_similar(x, y):
            if lens[x] != lens[y]:
                return False
            diffs = []
            for i in range(0, lens[x], L):
                if codes[x][i // L] != codes[y][i // L]:
                    for j in range(i, min(lens[x], i + L)):
                        if strs[x][j] != strs[y][j]:
                            diffs.append(j)
                            if len(diffs) > 2:
                                return False
            if len(diffs) == 0:
                return True
            if len(diffs) == 2:
                i, j = diffs[0], diffs[1]
                if (strs[x][i] == strs[y][j]) and (strs[x][j] == strs[y][i]):
                    return True
            return False

        fa = [i for i in range(n)]
        def get_root(fa, i):
            if fa[i] == i:
                return i
            fa[i] = get_root(fa, fa[i])
            return fa[i]

        for i in range(n):
            for j in range(i + 1, n):
                if is_similar(i, j):
                    root_i, root_j = get_root(fa, i), get_root(fa, j)
                    fa[root_i] = root_j
        return len([i for i in range(n) if fa[i] == i])
17300