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31 lines
1.1 KiB
HTML
31 lines
1.1 KiB
HTML
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<p><strong>「快乐前缀」</strong> 是在原字符串中既是 <strong>非空</strong> 前缀也是后缀（不包括原字符串自身）的字符串。</p>
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<p>给你一个字符串 <code>s</code>，请你返回它的 <strong>最长快乐前缀</strong>。如果不存在满足题意的前缀，则返回一个空字符串<meta charset="UTF-8" /> <code>""</code> 。</p>
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<p> </p>
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<p><strong>示例 1：</strong></p>
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<pre>
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<strong>输入：</strong>s = "level"
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<strong>输出：</strong>"l"
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<strong>解释：</strong>不包括 s 自己，一共有 4 个前缀（"l", "le", "lev", "leve"）和 4 个后缀（"l", "el", "vel", "evel"）。最长的既是前缀也是后缀的字符串是 "l" 。
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</pre>
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<p><strong>示例 2：</strong></p>
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<pre>
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<strong>输入：</strong>s = "ababab"
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<strong>输出：</strong>"abab"
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<strong>解释：</strong>"abab" 是最长的既是前缀也是后缀的字符串。题目允许前后缀在原字符串中重叠。
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</pre>
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<p> </p>
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<p><strong>提示：</strong></p>
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<ul>
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<li><code>1 <= s.length <= 10<sup>5</sup></code></li>
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<li><code>s</code> 只含有小写英文字母</li>
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</ul>
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