Pinely Round 2 (Div. 1 + Div. 2)
B
Split Sort
Codeforces
1100
原题
← AC →
翻译中…

You are given a permutation$^{\dagger}$ $p_1, p_2, \ldots, p_n$ of integers $1$ to $n$.

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You can change the current permutation by applying the following operation several (possibly, zero) times:

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  • choose some $x$ ($2 \le x \le n$);
  • create a new permutation by:
  • first, writing down all elements of $p$ that are less than $x$, without changing their order;
    • second, writing down all elements of $p$ that are greater than or equal to $x$, without changing their order;
  • replace $p$ with the newly created permutation.
翻译中…

For example, if the permutation used to be $[6, 4, 3, 5, 2, 1]$ and you choose $x = 4$, then you will first write down $[3, 2, 1]$, then append this with $[6, 4, 5]$. So the initial permutation will be replaced by $[3, 2, 1, 6, 4, 5]$.

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Find the minimum number of operations you need to achieve $p_i = i$ for $i = 1, 2, \ldots, n$. We can show that it is always possible to do so.

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$^{\dagger}$ 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).

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Input

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Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \le t \le 1000$). The description of the test cases follows.

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The first line of each test case contains one integer $n$ ($1 \le n \le 100\,000$).

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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 $p_1, p_2, \ldots, p_n$ is a permutation.

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It is guaranteed that the sum of $n$ over all test cases does not exceed $100\,000$.

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Output

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For each test case, output the answer on a separate line.

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Note

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In the first test case, $n = 1$ and $p_1 = 1$, so there is nothing left to do.

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In the second test case, we can choose $x = 2$ and we immediately obtain $p_1 = 1$, $p_2 = 2$.

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In the third test case, we can achieve the minimum number of operations in the following way:

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  1. $x = 4$: $[6, 4, 3, 5, 2, 1] \rightarrow [3, 2, 1, 6, 4, 5]$;
  2. $x = 6$: $[3, 2, 1, 6, 4, 5] \rightarrow [3, 2, 1, 4, 5, 6]$;
  3. $x = 3$: $[3, 2, 1, 4, 5, 6] \rightarrow [2, 1, 3, 4, 5, 6]$;
  4. $x = 2$: $[2, 1, 3, 4, 5, 6] \rightarrow [1, 2, 3, 4, 5, 6]$.
翻译中…

样例

Input #1
5
1
1
2
2 1
6
6 4 3 5 2 1
3
3 1 2
19
10 19 7 1 17 11 8 5 12 9 4 18 14 2 6 15 3 16 13
Output #1
0
1
4
1
7
InputCopy OutputCopy
题目信息
题号
1863B
时间限制
1 s
内存限制
256 MB
标签
贪心
数学
排序

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。