<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 find(vector<int>& par, int x) {
        return par[x]==x ? x : par[x]=find(par, par[x]);
    }
    
    void merge(vector<int>& par, int x, int y) {
        par[x] = y;
    }
    
    bool areSimilar(string& a, string& b) {
        if(a.size()!=b.size()) {
            return false;
        }
        
        vector<int> arr;
        for(int i=0; i<a.size(); i++) {
            if(a[i]!=b[i]) {
                if(arr.size()>2) {
                    return false;
                }
                arr.push_back(i);
            }
        }
        if(arr.size()==0) {
            return true;
        }
        if(arr.size()!=2) {
            return false;
        }
        
        return a[arr[0]]==b[arr[1]] && a[arr[1]]==b[arr[0]];
    }
    
    int numSimilarGroups(vector<string>& strs) {
        vector<int> par(strs.size());
        
        for(int i=0; i<strs.size(); i++) {
            par[i] = i;
        }
        
        int ans=strs.size();
        for(int i=0; i<strs.size(); i++) {
            for(int j=i+1; j<strs.size(); j++) {
                if(areSimilar(strs[i], strs[j])) {
                    int par1=find(par, i), par2=find(par, j);
                    if(par1!=par2) {
                        merge(par, par1, par2);
                        ans--;
                    }
                }
            }
        }
        
        return ans;
    }
};
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