Codeforces Round 842 (Div. 2)
B
Quick Sort
Codeforces
900
原题
← AC →
翻译中…

You are given a permutation$^\dagger$ $p$ of length $n$ and a positive integer $k \le n$.

翻译中…

In one operation, you:

翻译中…
  • Choose $k$ distinct elements $p_{i_1}, p_{i_2}, \ldots, p_{i_k}$.
  • Remove them and then add them sorted in increasing order to the end of the permutation.
翻译中…

For example, if $p = [2,5,1,3,4]$ and $k = 2$ and you choose $5$ and $3$ as the elements for the operation, then $[2, \color{red}{5}, 1, \color{red}{3}, 4] \rightarrow [2, 1, 4, \color{red}{3},\color{red}{5}]$.

翻译中…

Find the minimum number of operations needed to sort the permutation in increasing order. It can be proven that it is always possible to do so.

翻译中…

$^\dagger$ A permutation of length $n$ is an array consisting of $n$ distinct integers from $1$ to $n$ in arbitrary order. For example, $[2,3,1,5,4]$ is a permutation, but $[1,2,2]$ is not a permutation ($2$ appears twice in the array), and $[1,3,4]$ is also not a permutation ($n=3$ but there is $4$ in the array).

翻译中…

Input

翻译中…

The first line contains a single integer $t$ ($1 \le t \le 10^4$) — the number of test cases. The description of test cases follows.

翻译中…

The first line of each test case contains two integers $n$ and $k$ ($2 \le n \le 10^5$, $1 \le k \le n$).

翻译中…

The second line of each test case contains $n$ integers $p_1,p_2,\ldots, p_n$ ($1 \le p_i \le n$). It is guaranteed that $p$ is a permutation.

翻译中…

It is guaranteed that the sum of $n$ over all test cases does not exceed $10^5$.

翻译中…

Output

翻译中…

For each test case output a single integer — the minimum number of operations needed to sort the permutation. It can be proven that it is always possible to do so.

翻译中…

Note

翻译中…

In the first test case, the permutation is already sorted.

翻译中…

In the second test case, you can choose element $3$, and the permutation will become sorted as follows: $[\color{red}{3}, 1, 2] \rightarrow [1, 2, \color{red}{3}]$.

翻译中…

In the third test case, you can choose elements $3$ and $4$, and the permutation will become sorted as follows: $[1, \color{red}{3}, 2, \color{red}{4}] \rightarrow [1, 2, \color{red}{3},\color{red}{4}]$.

翻译中…

In the fourth test case, it can be shown that it is impossible to sort the permutation in $1$ operation. However, if you choose elements $2$ and $1$ in the first operation, and choose elements $3$ and $4$ in the second operation, the permutation will become sorted as follows: $[\color{red}{2}, 3, \color{red}{1}, 4] \rightarrow [\color{blue}{3}, \color{blue}{4}, \color{red}{1}, \color{red}{2}] \rightarrow [1,2, \color{blue}{3}, \color{blue}{4}]$.

翻译中…

样例

Input #1
4
3 2
1 2 3
3 1
3 1 2
4 2
1 3 2 4
4 2
2 3 1 4
Output #1
0
1
1
2
InputCopy OutputCopy
题目信息
题号
1768B
时间限制
1 s
内存限制
256 MB
标签
贪心
数学

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。