9616: ABC247 —— Ex - Rearranging Problem
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Description
There are $N$ people called Person $1$, Person $2$, $\dots$, Person $N$, lined up in a row in the order of $(1,2,\dots,N)$ from the front. Person $i$ is wearing Color $c_i$.
Takahashi repeated the following operation $K$ times: choose two People $i$ and $j$ arbitrarily and swap the positions of Person $i$ and Person $j$.
After the $K$ operations have ended, the color that the $i$-th person from the front is wearing coincided with $c_i$, for every integer $i$ such that $1 \leq i \leq N$.
How many possible permutations of people after the $K$ operations are there? Find the count modulo $998244353$.
Takahashi repeated the following operation $K$ times: choose two People $i$ and $j$ arbitrarily and swap the positions of Person $i$ and Person $j$.
After the $K$ operations have ended, the color that the $i$-th person from the front is wearing coincided with $c_i$, for every integer $i$ such that $1 \leq i \leq N$.
How many possible permutations of people after the $K$ operations are there? Find the count modulo $998244353$.
Input
Input is given from Standard Input in the following format:
```
$N$ $K$
$c_1$ $c_2$ $\dots$ $c_N$
```
```
$N$ $K$
$c_1$ $c_2$ $\dots$ $c_N$
```
Output
Print the answer.
Constraints
- $2 \leq N \leq 200000$
- $1 \leq K \leq 10^9$
- $1 \leq c_i \leq N$
- All values in input are integers.
- $1 \leq K \leq 10^9$
- $1 \leq c_i \leq N$
- All values in input are integers.
Sample 1 Input
4 1
1 1 2 1
Sample 1 Output
3
Here is a comprehensive list of possible Takahashi's operations and permutations of people after each operation.
- Swap the positions of Person 1 and Person 2, resulting in a permutation (2,1,3,4).
- Swap the positions of Person 1 and Person 4, resulting in a permutation (4,2,3,1).
- Swap the positions of Person 2 and Person 4, resulting in a permutation (1,4,3,2).
Sample 2 Input
3 3
1 1 2
Sample 2 Output
1
Here is an example of a possible sequence of Takahashi's operations.
-
In the 1-st operation, he swaps the positions of Person 1 and Person 3, resulting in a permutation (3,2,1).
In the 2-nd operation, he swaps the positions of Person 2 and Person 3, resulting in a permutation (2,3,1).
In the 3-rd operation, he swaps the positions of Person 1 and Person 3, resulting in a permutation (2,1,3).
Sample 3 Input
10 4
2 7 1 8 2 8 1 8 2 8
Sample 3 Output
132