<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:
    def kSimilarity(self, s1: str, s2: str) -> int:
        
        ss1 = []
        ss2 = []
        
        for i in range(len(s1)):
            if s1[i] != s2[i]:
                ss1.append(s1[i])
                ss2.append(s2[i])
                
        s1 = "".join(ss1)
        s2 = "".join(ss2)
        
        @cache
        def numSwaps(s1, spot):
            if not s1:
                return 0
            
            if s1[0] == s2[spot]:
                return numSwaps(s1[1:],spot + 1)
            
            minSwaps = math.inf
            for i in range(1, len(s1)):
                if s1[i] == s2[spot]:
                    # Remove first char
                    curSwaps = 1 + numSwaps(s1[1:i] + s1[0] + s1[i+1:], spot + 1)
                    minSwaps = min(minSwaps, curSwaps)
        
        
            return minSwaps
        
        return numSwaps(s1, 0)
        '''
        
        for i in range(len(ss1)):
            curTarget = ss2[i]
            if ss1[i] == curTarget:
                continue
            else:
                swaps += 1
                
            optimalSwap = False
            swapSpot = -1
            for j in range(i + 1, len(ss1)):
                
                if ss1[j] == curTarget:
                    if ss1[i] == ss2[j]:
                        optimalSwap = True
                        ss1[i], ss1[j] = ss1[j], ss1[i]
                        break
                    else:
                        swapSpot = j
            if not optimalSwap:
                ss1[i], ss1[swapSpot] = ss1[swapSpot], ss1[i]
                
        return swaps
        '''
23000