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43 lines
2.0 KiB
HTML
43 lines
2.0 KiB
HTML
<p>You are given a string <code>s</code> that consists of lowercase English letters.</p>
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<p>A string is called <strong>special</strong> if it is made up of only a single character. For example, the string <code>"abc"</code> is not special, whereas the strings <code>"ddd"</code>, <code>"zz"</code>, and <code>"f"</code> are special.</p>
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<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>
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<p>A <strong>substring</strong> is a contiguous <strong>non-empty</strong> sequence of characters within a string.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<pre>
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<strong>Input:</strong> s = "aaaa"
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> The longest special substring which occurs thrice is "aa": substrings "<u><strong>aa</strong></u>aa", "a<u><strong>aa</strong></u>a", and "aa<u><strong>aa</strong></u>".
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It can be shown that the maximum length achievable is 2.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> s = "abcdef"
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<strong>Output:</strong> -1
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<strong>Explanation:</strong> There exists no special substring which occurs at least thrice. Hence return -1.
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<pre>
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<strong>Input:</strong> s = "abcaba"
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<strong>Output:</strong> 1
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<strong>Explanation:</strong> The longest special substring which occurs thrice is "a": substrings "<u><strong>a</strong></u>bcaba", "abc<u><strong>a</strong></u>ba", and "abcab<u><strong>a</strong></u>".
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It can be shown that the maximum length achievable is 1.
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>3 <= s.length <= 5 * 10<sup>5</sup></code></li>
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<li><code>s</code> consists of only lowercase English letters.</li>
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</ul>
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