AtCoder Beginner Contest 207
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Problem Statement
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Given is a sequence $A$ of $N$ numbers. Find the number of ways to separate $A$ into some number of non-empty contiguous subsequence $B_1, B_2, \ldots, B_k$ so that the following condition is satisfied:
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- For every
$i\ (1 \leq i \leq k)$, the sum of elements in$B_i$is divisible by$i$.
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Since the count can be enormous, print it modulo $(10^9+7)$.
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Constraints
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$1 \leq N \leq 3000$$1 \leq A_i \leq 10^{15}$- All values in input are integers.
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Input
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Input is given from Standard Input in the following format:
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N
A_1 A_2 \ldots A_N
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Output
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Print the number of ways to separate the sequence so that the condition in the Problem Statement is satisfied, modulo $(10^9+7)$.
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样例
Input #1
4
1 2 3 4
Output #1
3
We have three ways to separate the sequence, as follows:
- $(1),(2),(3),(4)$
- $(1,2,3),(4)$
- $(1,2,3,4)$
Input #2
5
8 6 3 3 3
Output #2
5
Input #3
10
791754273866483 706434917156797 714489398264550 918142301070506 559125109706263 694445720452148 648739025948445 869006293795825 718343486637033 934236559762733
Output #3
15
The values in input may not fit into a $32$-bit integer type.
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。