<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>

from collections import Counter
class Solution:
    def maximumLength(self, s: str) -> int:
        def getMaxLength(lst):
            s = sorted(lst, reverse=True)
            if s[0]==s[2]:
                return s[0]
            #s[0]>s[2]
            if s[0]-2>=s[1]:
                return s[0]-2
            #s[0]>s[2] and s[0]<s[1]+2
            return s[0]-1

        n = len(s)
        if n == 3:
            return 1 if len(set(s))==1 else -1
        special=[[0]*(n) for _ in range(26)]
        special[ord(s[0])-ord('a')][0]=1
        for i in range(1,n):
            charIdx = ord(s[i])-ord('a')
            if s[i]==s[i-1]:
                special[charIdx][i] = special[charIdx][i-1]+1
                special[charIdx][i-1] = 0
            else:
                special[charIdx][i] = 1
        #print(special)
        ans = 0
        for i in range(26):
            ans     = max(ans, getMaxLength(special[i]))
            #print(f"{i} {special[i]} ans={ans}")
        return ans if ans!=0 else -1
1935