<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 vis[300];

    int comp(string a, string b) {
        char a1, a2, b1, b2;
        int cnt = 0;
        for (int i = 0; i < a.size(); i++) {
            if (a[i] != b[i]) {
                if (cnt >= 2) {
                    return 0;
                }
                if (cnt == 0) {
                    a1 = a[i];
                    b1 = b[i];
                }
                else {
                    a2 = a[i];
                    b2 = b[i];
                }
                cnt++;
            }
        }
        if (a1 == b2 && a2 == b1)
            return 1;
        if (cnt == 0)
            return 1;
        return 0;
    }

    void dfs(int i, vector<vector<int>> adj) {
        if (vis[i])
            return;
        vis[i] = 1;
        for (int j: adj[i]) {
            if (!vis[j])
                dfs(j, adj);
        }
    }


    int numSimilarGroups(vector<string>& strs) {
        vector<vector<int>> adj;
        for (int i = 0; i < strs.size(); i++) {
            vis[i] = 0;
            adj.push_back({});
        }
        for (int i = 0; i < strs.size(); i++) {
            for (int j = i+1; j < strs.size(); j++) {
                // check if these two can be in the same group
                if (comp(strs[i], strs[j])) {
                    adj[i].push_back(j);
                    adj[j].push_back(i);
                }
            }
        }
        int ans = 0;
        for (int i = 0; i < strs.size(); i++) {
            if (!vis[i]) {
                ans++;
                dfs(i, adj);
            }
        }
        return ans;
    }
};
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