<p>Strings <code>s1</code> and <code>s2</code> are <code>k</code><strong>-similar</strong> (for some non-negative integer <code>k</code>) if we can swap the positions of two letters in <code>s1</code> exactly <code>k</code> times so that the resulting string equals <code>s2</code>.</p>

<p>Given two anagrams <code>s1</code> and <code>s2</code>, return the smallest <code>k</code> for which <code>s1</code> and <code>s2</code> are <code>k</code><strong>-similar</strong>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s1 = &quot;ab&quot;, s2 = &quot;ba&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong> The two string are 1-similar because we can use one swap to change s1 to s2: &quot;ab&quot; --&gt; &quot;ba&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s1 = &quot;abc&quot;, s2 = &quot;bca&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> The two strings are 2-similar because we can use two swaps to change s1 to s2: &quot;abc&quot; --&gt; &quot;bac&quot; --&gt; &quot;bca&quot;.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s1.length &lt;= 20</code></li>
	<li><code>s2.length == s1.length</code></li>
	<li><code>s1</code> and <code>s2</code> contain only lowercase letters from the set <code>{&#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;, &#39;e&#39;, &#39;f&#39;}</code>.</li>
	<li><code>s2</code> is an anagram of <code>s1</code>.</li>
</ul>

class Solution {
public:
    // int fun(int ind,string s1,string s2,unordered_map<string,int>&dp)
    // {
        
    //     if(s1==s2)return 0;
    //     if(dp.find(s1)!=dp.end())return dp[s1];
    //     int ans=INT_MAX;
    //     if(s1[ind]!=s2[ind])
    //     {
    //        for(int j=ind;j<s1.length();j++)
    //        {
    //             if(s1[j]==s2[ind])
    //             {
    //             swap(s1[ind],s1[j]);
    //             ans=min(ans,1+fun(ind+1,s1,s2,dp));
    //             swap(s1[ind],s1[j]);
    //             }
                
    //        }
    //     }
    //     else 
    //      ans=fun(ind+1,s1,s2,dp);

    //  return dp[s1]=ans;
         
          
    // }
    int kSimilarity(string s1, string s2) {
         
        //   unordered_map<string,int>dp;
        //   return fun(0,s1,s2,dp);
        queue<pair<int,string>>q;
         unordered_set<string> vis;
        q.push({0,s1});
        vis.insert(s1);
        string s="abcdef";
        int ans=INT_MAX;
        while(!q.empty())
        {
             auto u=q.front();
             int val=u.first;
             string st=u.second;
             q.pop();
             if(st==s2)
             {
                 ans=min(val,ans);
                 return ans;
             }
             for(int i=0;i<st.length();i++)
             {
                 if(st[i]!=s2[i])
                 {
                     for(int j=i+1;j<st.length();j++)
                     {
                         if(st[j]==s2[i])
                         {
                             swap(st[i],st[j]);
                             if(!vis.count(st))
                             {
                             q.push({val+1,st});
                              vis.insert(st);
                             }
                             swap(st[i],st[j]);
                         }
                     }
                     break;
                 }

             }
        }
        return -1;
        
    }
};
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