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Time Limit: 2 s Memory Limit: 128 MB Total points: 100

#16224. 双递增序列

Statistics

考虑一个长度为偶数 $n$ 的序列 $a_1,a_2,\cdots,a_n$,我们称这个序列为好的,当且仅当存在在 $a_1,a_2,\cdots,a_n$ 的一个划分 $U=\{a_{i_1},a_{i_2},\cdots,a_{i_{n/2}}\}$, $V=\{a_{j_1},a_{j_2},\cdots,a_{j_{n/2}}\}=\{a_1,a_2,\cdots,a_n\}-U$,且 $i_1< i_2< \cdots< i_{n/2}$, $a_{i_1}< a_{i_2}<\cdots< a_{i_{n/2}}$, $j_1< j_2< \cdots< j_{n/2}$, $a_{j_1}< a_{j_2}< \cdots< a_{j_{n/2}}$。

比如序列 $3,1,4,5,8,7$ 就是一个好的序列,因为它可以分成 $U=\{3,4,8\},V=\{1,5,7\}$。而序列 $3,2,1,6,5,4$ 则不是一个好的序列。

现在的问题是,针对给出的若干序列,请你判断它们是否是好的序列。

输入格式(input.txt)

第一行仅包含一个整数 $m$,表示需要判断 $m$ 个序列。接下来的 $m$ 行分别给出这些序列。每个序列的输入为 1 行,每行的第 1 个数为一个偶数 $n$,表示序列的长度,随后 $n$ 个整数表示序列本身的元素 $a_1,a_2,\cdots,a_n$。同一行的各数之间用一个空格隔开。

输出格式(output.txt)

输出一共有 $m$ 行,如果第 $i$ 个序列为好的序列,那么第 $i$ 行输出 Yes!,否则输出 No!

样例数据

输入

2
6 3 1 4 5 8 7
6 3 2 1 6 5 4

输出

Yes!
No!

子任务

  • 10% 的数据:$n \le 100$
  • 40% 的数据:$n \le 300$
  • 100% 的数据:$n \le 2000$
  • 100% 的数据:$m \le 25,\ 0 \le a_1,a_2,\cdots,a_n \le 10^6$

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