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# 2014. Longest Subsequence Repeated k Times

<https://leetcode.com/problems/longest-subsequence-repeated-k-times>

## Description

You are given a string `s` of length `n`, and an integer `k`. You are tasked to find the **longest subsequence repeated** `k` times in string `s`.

A **subsequence** is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.

A subsequence `seq` is **repeated** `k` times in the string `s` if `seq * k` is a subsequence of `s`, where `seq * k` represents a string constructed by concatenating `seq` `k` times.

* For example, `"bba"` is repeated `2` times in the string `"bababcba"`, because the string `"bbabba"`, constructed by concatenating `"bba"` `2` times, is a subsequence of the string `"**b**a**bab**c**ba**"`.

Return *the **longest subsequence repeated*** `k` *times in string* `s`*. If multiple such subsequences are found, return the **lexicographically largest** one. If there is no such subsequence, return an **empty** string*.

**Example 1:**

![example 1](https://assets.leetcode.com/uploads/2021/08/30/longest-subsequence-repeat-k-times.png)

```
**Input:** s = "letsleetcode", k = 2
**Output:** "let"
**Explanation:** There are two longest subsequences repeated 2 times: "let" and "ete".
"let" is the lexicographically largest one.
```

**Example 2:**

```
**Input:** s = "bb", k = 2
**Output:** "b"
**Explanation:** The longest subsequence repeated 2 times is "b".
```

**Example 3:**

```
**Input:** s = "ab", k = 2
**Output:** ""
**Explanation:** There is no subsequence repeated 2 times. Empty string is returned.
```

**Example 4:**

```
**Input:** s = "bbabbabbbbabaababab", k = 3
**Output:** "bbbb"
**Explanation:** The longest subsequence "bbbb" is repeated 3 times in "bbabbabbbbabaababab".
```

**Constraints:**

* `n == s.length`
* `2 <= n, k <= 2000`
* `2 <= n < k * 8`
* `s` consists of lowercase English letters.

## ac

```java
```