9270: ABC295 —— E - Kth Number
[Creator : ]
Description
### Problem Statement
We have a sequence of length $N$ consisting of integers between $0$ and $M$, inclusive: $A=(A_1,A_2,\dots,A_N)$.
Snuke will perform the following operations 1 and 2 in order.
1. For each $i$ such that $A_i=0$, independently choose a uniform random integer between $1$ and $M$, inclusive, and replace $A_i$ with that integer.
2. Sort $A$ in ascending order.
Print the expected value of $A_K$ after the two operations, modulo $998244353$.
How to print a number modulo $998244353$? It can be proved that the sought expected value is always rational. Additionally, under the Constraints of this problem, when that value is represented as $\frac{P}{Q}$ using two coprime integers $P$ and $Q$, it can be proved that there is a unique integer $R$ such that $R \times Q \equiv P\pmod{998244353}$ and $0 \leq R \lt 998244353$. Print this $R$.
We have a sequence of length $N$ consisting of integers between $0$ and $M$, inclusive: $A=(A_1,A_2,\dots,A_N)$.
Snuke will perform the following operations 1 and 2 in order.
1. For each $i$ such that $A_i=0$, independently choose a uniform random integer between $1$ and $M$, inclusive, and replace $A_i$ with that integer.
2. Sort $A$ in ascending order.
Print the expected value of $A_K$ after the two operations, modulo $998244353$.
How to print a number modulo $998244353$? It can be proved that the sought expected value is always rational. Additionally, under the Constraints of this problem, when that value is represented as $\frac{P}{Q}$ using two coprime integers $P$ and $Q$, it can be proved that there is a unique integer $R$ such that $R \times Q \equiv P\pmod{998244353}$ and $0 \leq R \lt 998244353$. Print this $R$.
Input
### Input
The input is given from Standard Input in the following format:
```
$N$ $M$ $K$
$A_1$ $A_2$ $\dots$ $A_N$
```
The input is given from Standard Input in the following format:
```
$N$ $M$ $K$
$A_1$ $A_2$ $\dots$ $A_N$
```
Output
### Output
Print the expected value of $A_K$ after the two operations, modulo $998244353$.
Print the expected value of $A_K$ after the two operations, modulo $998244353$.
Constraints
### Constraints
- $1\leq K \leq N \leq 2000$
- $1\leq M \leq 2000$
- $0\leq A_i \leq M$
- All values in the input are integers.
- $1\leq K \leq N \leq 2000$
- $1\leq M \leq 2000$
- $0\leq A_i \leq M$
- All values in the input are integers.
Sample 1 Input
3 5 2
2 0 4
Sample 1 Output
3
In the operation 1, Snuke will replace $A_2$ with an integer between 1 and 5. Let x be this integer.
- If x=1 or 2, we will have $A_2=2$ after the two operations.
- If x=3, we will have $A_2=3$ after the two operations.
- If x=4 or 5, we will have $A_2=4$ after the two operations.
Sample 2 Input
2 3 1
0 0
Sample 2 Output
221832080
The expected value is $\frac{14}{9}$.
Sample 3 Input
10 20 7
6 5 0 2 0 0 0 15 0 0
Sample 3 Output
617586310