<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:
    vector<int> parents;

    bool issimilar(string &a, string &b)
    {
        int diff = 0;

        for (int i=0;i<a.length(); i++)
        {
            if (a[i] != b[i])
                diff++;
        }

        return diff == 2 || diff == 0;
    }

    void unionstr(int i, int j, vector<string>& strs)
    {
        int x_parent = find(i);
        int y_parent = find(j);

        if (x_parent == y_parent)
        {
            return;
        }

        string a = strs[i];
        string b = strs[j];
        bool same = issimilar(a,b);
        if(same)
        {
            parents[y_parent] = x_parent;
        }
    }

    int find(int x)
    {
        if (x == parents[x])
        {
            return x;
        }

        return parents[x] = find(parents[x]);
    }

    int numSimilarGroups(vector<string>& strs) {
        int n = strs.size();
        parents.resize(n+1);
        for(int i=0; i<n; i++) parents[i] = i;

        for (int i=0; i<n; i++)
        {
            for (int j=i+1; j<n; j++)
            {
                unionstr(i, j, strs);
            }
        }

        // Count distinct root parents
        int num_groups = 0;
        for (int i = 0; i < n; i++) {
            if (find(i) == i) {
                num_groups++;
            }
        }

        return num_groups;
    }
};
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