<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 bfs(string str, unordered_map<string, vector<string>>& adj, unordered_set<string>& st){

    queue<string> q;
    q.push(str);
    st.insert(str);
    
    while(!q.empty()){
      int m=q.size();
      string temp=q.front();
      q.pop();

      while(m--){
        for(auto it: adj[temp])
          if(st.find(it)==st.end()){
            st.insert(it);
            q.push(it);
          }        
      }
    }
    
  }



  bool isSame(string& s1, string& s2){
    
    int n=s1.size();
    int m=s2.size();
    if(n!=m)return false;
    int diff=0;
    for(int i=0; i<n; i++){
      if(s1[i]!=s2[i])
        diff++;
    }
    if(diff==0 || diff==2){
      return true;
    }
    return false;
  }

    int numSimilarGroups(vector<string>& strs) {
        
      int n=strs.size();
      unordered_map<string, vector<string>> adj;
      for(int i=0; i<n; i++){
        for(int j=i+1; j<n; j++){
          if(isSame(strs[i], strs[j])){
            adj[strs[i]].push_back(strs[j]);
            adj[strs[j]].push_back(strs[i]);
          }
        }
      }

      int grp=0;
      unordered_set<string> st;
      for(int i=0; i<n; i++){
        if(st.find(strs[i])==st.end()){
          grp++;
          bfs(strs[i], adj, st);
        }
      }
      return grp;
    }
};
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