Codeforces Round 630 (Div. 2) |
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Finished |
Word $$$s$$$ of length $$$n$$$ is called $$$k$$$-complete if
For example, "abaaba" is a $$$3$$$-complete word, while "abccba" is not.
Bob is given a word $$$s$$$ of length $$$n$$$ consisting of only lowercase Latin letters and an integer $$$k$$$, such that $$$n$$$ is divisible by $$$k$$$. He wants to convert $$$s$$$ to any $$$k$$$-complete word.
To do this Bob can choose some $$$i$$$ ($$$1 \le i \le n$$$) and replace the letter at position $$$i$$$ with some other lowercase Latin letter.
So now Bob wants to know the minimum number of letters he has to replace to convert $$$s$$$ to any $$$k$$$-complete word.
Note that Bob can do zero changes if the word $$$s$$$ is already $$$k$$$-complete.
You are required to answer $$$t$$$ test cases independently.
The first line contains a single integer $$$t$$$ ($$$1 \le t\le 10^5$$$) — the number of test cases.
The first line of each test case contains two integers $$$n$$$ and $$$k$$$ ($$$1 \le k < n \le 2 \cdot 10^5$$$, $$$n$$$ is divisible by $$$k$$$).
The second line of each test case contains a word $$$s$$$ of length $$$n$$$.
It is guaranteed that word $$$s$$$ only contains lowercase Latin letters. And it is guaranteed that the sum of $$$n$$$ over all test cases will not exceed $$$2 \cdot 10^5$$$.
For each test case, output one integer, representing the minimum number of characters he has to replace to convert $$$s$$$ to any $$$k$$$-complete word.
4 6 2 abaaba 6 3 abaaba 36 9 hippopotomonstrosesquippedaliophobia 21 7 wudixiaoxingxingheclp
2 0 23 16
In the first test case, one optimal solution is aaaaaa.
In the second test case, the given word itself is $$$k$$$-complete.
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