AtCoder Regular Contest 206 (Div. 2)
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Problem Statement
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You are given a sequence $A=(A_1,\ldots,A_N)$ of length $N$. You perform the following operation exactly once.
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- Choose a pair of integers
$(L,R)$such that$1\leq L \leq R \leq N$. Replace each of$A_L,A_{L+1},\ldots,A_R$with$A_L$.
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How many different sequences are possible as $A$ after the operation?
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Constraints
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- All input values are integers.
$1 \leq N \leq 10^6$$1\leq A_i \leq N$
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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
A_1 \ldots A_N
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Output
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Output the answer.
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样例
Input #1
4
1 1 2 3
Output #1
4
The possible sequences after the operation are the following four sequences:
- $(1,1,1,1)$
- $(1,1,1,3)$
- $(1,1,2,2)$
- $(1,1,2,3)$
For example, $(1,1,1,3)$ can be obtained by performing the operation with $L=2,R=3$.
Input #2
10
2 5 6 5 2 1 7 9 7 2
Output #2
41
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。