CF1768B.Quick Sort

传统题 时间 2000 ms 内存 256 MiB 4 尝试 1 已通过 1 标签

Quick Sort

You are given a permutation^\dagger pp of length nn and a positive integer knk \le n.

In one operation, you:

  • Choose kk distinct elements pi1,pi2,,pikp_{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.

For example, if p=[2,5,1,3,4]p = [2,5,1,3,4] and k=2k = 2 and you choose 55 and 33 as the elements for the operation, then $[2, \color{red}{5}, 1, \color{red}{3}, 4] \rightarrow [2, 1, 4, \color{red}{3},\color{red}{5}]$.

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.

^\dagger A permutation of length nn is an array consisting of nn distinct integers from 11 to nn in arbitrary order. For example, [2,3,1,5,4][2,3,1,5,4] is a permutation, but [1,2,2][1,2,2] is not a permutation (22 appears twice in the array), and [1,3,4][1,3,4] is also not a permutation (n=3n=3 but there is 44 in the array).

Input

The first line contains a single integer tt (1t1041 \le t \le 10^4) — the number of test cases. The description of test cases follows.

The first line of each test case contains two integers nn and kk (2n1052 \le n \le 10^5, 1kn1 \le k \le n).

The second line of each test case contains nn integers p1,p2,,pnp_1,p_2,\ldots, p_n (1pin1 \le p_i \le n). It is guaranteed that pp is a permutation.

It is guaranteed that the sum of nn over all test cases does not exceed 10510^5.

Output

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.

Note

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

In the second test case, you can choose element 33, and the permutation will become sorted as follows: $[\color{red}{3}, 1, 2] \rightarrow [1, 2, \color{red}{3}]$.

In the third test case, you can choose elements 33 and 44, and the permutation will become sorted as follows: $[1, \color{red}{3}, 2, \color{red}{4}] \rightarrow [1, 2, \color{red}{3},\color{red}{4}]$.

In the fourth test case, it can be shown that it is impossible to sort the permutation in 11 operation. However, if you choose elements 22 and 11 in the first operation, and choose elements 33 and 44 in the second operation, the permutation will become sorted as follows: $[\color{red}{2}, 3, \color{red}{1}, 4] \rightarrow [\color{blue}{3}, \color{blue}{4}, \color{red}{1}, \color{red}{2}] \rightarrow [1,2, \color{blue}{3}, \color{blue}{4}]$.

Samples

4
3 2
1 2 3
3 1
3 1 2
4 2
1 3 2 4
4 2
2 3 1 4
0
1
1
2

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