AtCoder Beginner Contest 169
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Problem Statement
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Given are a sequence of $N$ positive integers $A_1$, $A_2$, $\ldots$, $A_N$ and another positive integer $S$.
For a non-empty subset $T$ of the set $\{1, 2, \ldots , N \}$, let us define $f(T)$ as follows:
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$f(T)$is the number of different non-empty subsets$\{x_1, x_2, \ldots , x_k \}$of$T$such that$A_{x_1}+A_{x_2}+\cdots +A_{x_k} = S$.
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Find the sum of $f(T)$ over all $2^N-1$ subsets $T$ of $\{1, 2, \ldots , N \}$. Since the sum can be enormous, print it modulo $998244353$.
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Constraints
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- All values in input are integers.
$1 \leq N \leq 3000$$1 \leq S \leq 3000$$1 \leq A_i \leq 3000$
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Input
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Input is given from Standard Input in the following format:
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N S
A_1 A_2 ... A_N
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Output
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Print the sum of $f(T)$ modulo $998244353$.
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样例
Input #1
3 4
2 2 4
Output #1
6
For each $T$, the value of $f(T)$ is shown below. The sum of these values is $6$.
- $f(\{1\}) = 0$
- $f(\{2\}) = 0$
- $f(\{3\}) = 1$ (One subset $\{3\}$ satisfies the condition.)
- $f(\{1, 2\}) = 1$ ($\{1, 2\}$)
- $f(\{2, 3\}) = 1$ ($\{3\}$)
- $f(\{1, 3\}) = 1$ ($\{3\}$)
- $f(\{1, 2, 3\}) = 2$ ($\{1, 2\}, \{3\}$)
Input #2
5 8
9 9 9 9 9
Output #2
0
Input #3
10 10
3 1 4 1 5 9 2 6 5 3
Output #3
3296
题目信息
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。