<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 {
    int comp;
    vector<int> root;

    int find(int x) {
        if(root[x] == x || root[x] == -1) return root[x] = x;
        return root[x] = find(root[x]);
    }

    void unionSet(int a, int b) {
        int ra = find(a), rb = find(b);
        if(ra != rb) {
            root[ra] = rb;
            comp--;
        }
    }

    bool similar(string & a, string & b) {
        int sz = a.size();
        vector<char> da,db;
        for(int i = 0;i < sz;i++) {
            if(a[i] != b[i]) {
                da.push_back(a[i]);
                db.push_back(b[i]);
                if(da.size() > 2) return false;
            }
        }
        return da[0] == db[1] && db[0] == da[1];
    }
public:
    int numSimilarGroups(vector<string>& strs) {
        comp = strs.size();
        int sz = strs.size();
        root.resize(sz, -1);
        for(int i = 0;i < sz;i++) {
            for(int j = i + 1;j < sz;j++) {
                if(strs[i] == strs[j] || similar(strs[i], strs[j])) {
                    unionSet(i, j);
                }
            }
        }
        return comp;
    }
};
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