AtCoder Regular Contest 156
B
Mex on Blackboard
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原题
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Problem Statement

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For a finite multiset $S$ of non-negative integers, let us define $\mathrm{mex}(S)$ as the smallest non-negative integer not in $S$. For instance, $\mathrm{mex}(\lbrace 0,0, 1,3\rbrace ) = 2, \mathrm{mex}(\lbrace 1 \rbrace) = 0, \mathrm{mex}(\lbrace \rbrace) = 0$.

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There are $N$ non-negative integers on a blackboard. The $i$-th integer is $A_i$.

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You will perform the following operation exactly $K$ times.

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  • Choose zero or more integers on the blackboard. Let $S$ be the multiset of chosen integers, and write $\mathrm{mex}(S)$ on the blackboard once.
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How many multisets can be the multiset of integers on the final blackboard? Find this count modulo $998244353$.

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Constraints

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  • $1 \leq N,K \leq 2\times 10^5$
  • $0\leq A_i\leq 2\times 10^5$
  • All numbers in the input are integers.
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Input

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The input is given from Standard Input in the following format:

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N K
A_1 A_2 \ldots A_N

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Output

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Print the answer.

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样例

Input #1
3 1
0 1 3
Output #1
3
The following three multisets can be obtained by the operations. - $\lbrace 0,0,1,3 \rbrace$ - $\lbrace 0,1,1,3\rbrace$ - $\lbrace 0,1,2,3 \rbrace$ For instance, you can get $\lbrace 0,1,1,3\rbrace$ by choosing the $0$ on the blackboard to let $S=\lbrace 0\rbrace$ in the operation.
Input #2
2 1
0 0
Output #2
2
The following two multisets can be obtained by the operations. - $\lbrace 0,0,0 \rbrace$ - $\lbrace 0,0,1\rbrace$ Note that you may choose zero integers in the operation.
Input #3
5 10
3 1 4 1 5
Output #3
7109
题目信息
题号
arc156_b
时间限制
2 s
内存限制
1024 MB

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