AtCoder Regular Contest 064
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Problem Statement
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Takahashi and Aoki are going to together construct a sequence of integers.
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First, Takahashi will provide a sequence of integers $a$, satisfying all of the following conditions:
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- The length of
$a$is$N$. - Each element in
$a$is an integer between$1$and$K$, inclusive. $a$is a palindrome, that is, reversing the order of elements in$a$will result in the same sequence as the original.
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Then, Aoki will perform the following operation an arbitrary number of times:
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- Move the first element in
$a$to the end of$a$.
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How many sequences $a$ can be obtained after this procedure, modulo $10^9+7$?
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Constraints
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$1≤N≤10^9$$1≤K≤10^9$
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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
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Output
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Print the number of the sequences $a$ that can be obtained after the procedure, modulo $10^9+7$.
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样例
Input #1
4 2
Output #1
6
The following six sequences can be obtained:
- $(1, 1, 1, 1)$
- $(1, 1, 2, 2)$
- $(1, 2, 2, 1)$
- $(2, 2, 1, 1)$
- $(2, 1, 1, 2)$
- $(2, 2, 2, 2)$
Input #2
1 10
Output #2
10
Input #3
6 3
Output #3
75
Input #4
1000000000 1000000000
Output #4
875699961
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。