题库练习 Unforgivable Curse (hard version)
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A15843 | Unforgivable Curse (hard version)

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题目描述

This is a complex version of the problem. This version has no additional restrictions on the number $k$ .

The chief wizard of the Wizengamot once caught the evil wizard Drahyrt, but the evil wizard has returned and wants revenge on the chief wizard. So he stole spell $s$ from his student Harry.

The spell — is a $n$ -length string of lowercase Latin letters.

Drahyrt wants to replace spell with an unforgivable curse — string $t$ .

Dragirt, using ancient magic, can swap letters at a distance $k$ or $k+1$ in spell as many times as he wants. In other words, Drahyrt can change letters in positions $i$ and $j$ in spell $s$ if $|i-j|=k$ or $|i-j|=k+1$ .

For example, if $k = 3, s = $ "talant" and $t = $ "atltna", Drahyrt can act as follows:

- swap the letters at positions $1$ and $4$ to get spell "aaltnt".
- swap the letters at positions $2$ and $6$ to get spell "atltna".

You are given spells $s$ and $t$ . Can Drahyrt change spell $s$ to $t$ ?

输入格式

The first line of input gives a single integer $T$ ( $1 \le T \le 10^4$ ) — the number of test cases in the test.

Descriptions of the test cases are follow.

The first line contains two integers $n, k$ ( $1 \le n \le 2 \cdot 10^5$ , $1 \le k \le 2 \cdot 10^5$ ) — the length spells and the number $k$ such that Drahyrt can change letters in a spell at a distance $k$ or $k+1$ .

The second line gives spell $s$ — a string of length $n$ consisting of lowercase Latin letters.

The third line gives spell $t$ — a string of length $n$ consisting of lowercase Latin letters.

It is guaranteed that the sum of $n$ values over all test cases does not exceed $2 \cdot 10^5$ . Note that there is no limit on the sum of $k$ values over all test cases.

输出格式

For each test case, output on a separate line "YES" if Drahyrt can change spell $s$ to $t$ and "NO" otherwise.

You can output the answer in any case (for example, lines "yEs", "yes", "Yes" and "YES" will be recognized as positive answer).

输入输出样例

输入 #1
7
6 3
talant
atltna
7 1
abacaba
aaaabbc
12 6
abracadabraa
avadakedavra
5 3
accio
cicao
5 4
lumos
molus
4 3
uwjt
twju
4 3
kvpx
vxpk
输出 #1
YES
YES
NO
YES
NO
YES
NO
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