<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:
    void dfs(string src, unordered_map<string, vector<string>> &adj, unordered_map<string, bool> &visited) {
        visited[src] = true;
        for(auto nbr: adj[src]){
            if(!visited[nbr]){
                dfs(nbr, adj, visited);
            }
        }
        
        return;
    }
    
    bool is_similar(string &a, string &b){
        int i=0;
        int n = a.length();
        int cnt=0;
        while(i<n){
           if(a[i]!=b[i]) cnt++;
           if(cnt>2) return false;
           i++;
        }
        return cnt==2 || cnt==0;
    }
    int numSimilarGroups(vector<string>& strs) {
        int i = 0;
        int n = strs.size();
        unordered_map<string, vector<string>> adj;
        unordered_map<string, bool> visited;
        
        while(i<n){
            visited[strs[i]]=false;
            for(int j=0;j<n;j++){
                if(j==i || strs[i]==strs[j]) continue;
                if(is_similar(strs[i],strs[j])){
                    adj[strs[i]].push_back(strs[j]);
                    adj[strs[j]].push_back(strs[i]);
                }
            }
            
            i++;
        }
        
        int res=0;
        for(int i=0; i<n;i++){
            if(!visited[strs[i]]){
                res++;
                dfs(strs[i], adj, visited);
            }
        }
        
        return res;
        
    }
};
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