<p>You are given a string <code>s</code> that consists of lowercase English letters.</p>

<p>A string is called <strong>special</strong> if it is made up of only a single character. For example, the string <code>&quot;abc&quot;</code> is not special, whereas the strings <code>&quot;ddd&quot;</code>, <code>&quot;zz&quot;</code>, and <code>&quot;f&quot;</code> are special.</p>

<p>Return <em>the length of the <strong>longest special substring</strong> of </em><code>s</code> <em>which occurs <strong>at least thrice</strong></em>, <em>or </em><code>-1</code><em> if no special substring occurs at least thrice</em>.</p>

<p>A <strong>substring</strong> is a contiguous <strong>non-empty</strong> sequence of characters within a string.</p>

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

<pre>
<strong>Input:</strong> s = &quot;aaaa&quot;
<strong>Output:</strong> 2
<strong>Explanation:</strong> The longest special substring which occurs thrice is &quot;aa&quot;: substrings &quot;<u><strong>aa</strong></u>aa&quot;, &quot;a<u><strong>aa</strong></u>a&quot;, and &quot;aa<u><strong>aa</strong></u>&quot;.
It can be shown that the maximum length achievable is 2.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;abcdef&quot;
<strong>Output:</strong> -1
<strong>Explanation:</strong> There exists no special substring which occurs at least thrice. Hence return -1.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;abcaba&quot;
<strong>Output:</strong> 1
<strong>Explanation:</strong> The longest special substring which occurs thrice is &quot;a&quot;: substrings &quot;<u><strong>a</strong></u>bcaba&quot;, &quot;abc<u><strong>a</strong></u>ba&quot;, and &quot;abcab<u><strong>a</strong></u>&quot;.
It can be shown that the maximum length achievable is 1.
</pre>

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

<ul>
	<li><code>3 &lt;= s.length &lt;= 5 * 10<sup>5</sup></code></li>
	<li><code>s</code> consists of only lowercase English letters.</li>
</ul>

class Solution:
    def maximumLength(self, s: str) -> int:
        
        # we borrow some code from #2981:
        
        withCounts = [
            (L, 1)
            for L in s
        ]
        # print(f'{withCounts=}')
        for i in range(1, len(withCounts)):
            (prevLetter, prevCount) = withCounts[i - 1]
            (nextLetter, nextCount) = withCounts[i]
            # add counts together for same letter
            if prevLetter == nextLetter:
                withCounts[i - 1] = None
                withCounts[i] = (prevLetter, prevCount + nextCount)
        # print(f'{withCounts=}')
        withCounts = [
            W
            for W in withCounts
            if W is not None
        ]
        # print(f'{withCounts=}')

        specialCounts = Counter()
        for W in withCounts:
            print(f'{W=}')
            specialCounts[W] += 1
            (Letter, count) = W
            for i, C in enumerate(reversed(range(1, count))):
                W2 = (Letter, C)
                specialCounts[W2] += (i + 2)    # 1 for 0-index, 1 for we already did W
                print(f'  +{W2}')
                if specialCounts[W2] >= 3:
                    print(f'    Stop')
                    break
        print(f'{specialCounts=}')

        thrice = [
            W
            for W, count in specialCounts.items()
            if count >= 3
        ]
        print(f'{thrice=}')

        answers = [
            Size
            for (Letter, Size) in thrice
        ]
        print(f'{answers=}')
        return max(answers, default=-1)

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