longest-happy-prefix

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Algorithms

A string is called a happy prefix if is a non-empty prefix which is also a suffix (excluding itself).

Given a string <code>s</code>, return the longest happy prefix of <code>s</code>. Return an empty string <code>&quot;&quot;</code> if no such prefix exists.

&nbsp;
Example 1:

<pre>
Input: s = &quot;level&quot;
Output: &quot;l&quot;
Explanation: s contains 4 prefix excluding itself (&quot;l&quot;, &quot;le&quot;, &quot;lev&quot;, &quot;leve&quot;), and suffix (&quot;l&quot;, &quot;el&quot;, &quot;vel&quot;, &quot;evel&quot;). The largest prefix which is also suffix is given by &quot;l&quot;.
</pre>

Example 2:

<pre>
Input: s = &quot;ababab&quot;
Output: &quot;abab&quot;
Explanation: &quot;abab&quot; is the largest prefix which is also suffix. They can overlap in the original string.
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= s.length &lt;= 105</code></li>
	<li><code>s</code> contains only lowercase English letters.</li>
</ul>

longestPrefix

Longest Happy Prefix

Sum of Scores of Built Strings

sum-of-scores-of-built-strings

构造字符串的总得分和

Maximum Deletions on a String

maximum-deletions-on-a-string

对字母串可执行的最大删除数

Minimum Time to Revert Word to Initial State II

minimum-time-to-revert-word-to-initial-state-ii

将单词恢复初始状态所需的最短时间 II

Minimum Time to Revert Word to Initial State I

minimum-time-to-revert-word-to-initial-state-i

将单词恢复初始状态所需的最短时间 I

String

String Matching

Hash Function

Rolling Hash

「快乐前缀」&nbsp;是在原字符串中既是&nbsp;非空 前缀也是后缀（不包括原字符串自身）的字符串。

给你一个字符串 <code>s</code>，请你返回它的 最长快乐前缀。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" />&nbsp;<code>""</code>&nbsp;。

&nbsp;

示例 1：

<pre>
输入：s = "level"
输出："l"
解释：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" 。
</pre>

示例 2：

<pre>
输入：s = "ababab"
输出："abab"
解释："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。
</pre>

&nbsp;

提示：

<ul>
	<li><code>1 &lt;= s.length &lt;= 105</code></li>
	<li><code>s</code> 只含有小写英文字母</li>
</ul>