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QOJ

Time Limit: 3 s Memory Limit: 1024 MB Total points: 100

#5826. 错排

Statistics

小 X 最近学习了错排问题,于是开始思考一个关于它的变种问题:有多少个长度为 $n$ 的排列 $p$,满足对于 $i \le m$ 的位置满足 $p_i > m$,且对于所有位置 $i$ 都满足 $p_i \neq i$?

小 X 一共想出了 $T$ 个这样的问题,你能告诉他每个问题的答案吗?

由于答案可能过大,你只需要求出答案对 $998244353$ 取模后的值即可。

输入格式

第一行输入一个整数 $T$,表示询问组数。

接下来的 $T$ 行,每行输入两个整数 $n, m$。

输出格式

输出 $T$ 行,每行一个整数表示答案对 $998244353$ 取模后的值。

样例

输入 1

6
8 0
8 4
100 10
1000 100
10000 1000
100000 10000

输出 1

14833
576
548326276
694205000
493811811
135068319

数据范围

对于 $100\%$ 的数据,$0 \le T \le 2 \times 10^5$,$0 \le m \le n \le 2 \times 10^5$。

本题采用子任务捆绑测试。

  • subtask1(1pts):保证 $T = 0$。
  • subtask2(9pts):保证 $T \le 10$,$n, m \le 8$。
  • subtask3(10pts):保证 $m = 0$。
  • subtask4(20pts):保证 $n, m \le 5000$。
  • subtask5(20pts):保证 $T \le 10$。
  • subtask6(40pts):无特殊性质。

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