Codeforces Round 251 (Div. 2)
E
Devu and Birthday Celebration
Codeforces
2100
原题
← D→
翻译中…

Today is Devu's birthday. For celebrating the occasion, he bought $*n*$ sweets from the nearby market. He has invited his $*f*$ friends. He would like to distribute the sweets among them. As he is a nice guy and the occasion is great, he doesn't want any friend to be sad, so he would ensure to give at least one sweet to each friend.

翻译中…

He wants to celebrate it in a unique style, so he would like to ensure following condition for the distribution of sweets. Assume that he has distributed $*n*$ sweets to his friends such that $*i*^{*th*}$ friend is given $*a*_{*i*}$ sweets. He wants to make sure that there should not be any positive integer $*x* > 1$, which divides every $*a*_{*i*}$.

翻译中…

Please find the number of ways he can distribute sweets to his friends in the required way. Note that the order of distribution is important, for example [1, 2] and [2, 1] are distinct distributions. As the answer could be very large, output answer modulo $1000000007$ $(10^{9} + 7)$.

翻译中…

To make the problem more interesting, you are given $*q*$ queries. Each query contains an $*n*$, $*f*$ pair. For each query please output the required number of ways modulo $1000000007$ $(10^{9} + 7)$.

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Input

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The first line contains an integer $*q*$ representing the number of queries $(1 ≤ *q* ≤ 10^{5})$. Each of the next $*q*$ lines contains two space space-separated integers $*n*$, $*f*$ $(1 ≤ *f* ≤ *n* ≤ 10^{5})$.

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Output

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For each query, output a single integer in a line corresponding to the answer of each query.

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Note

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For first query: $*n* = 6, *f* = 2$. Possible partitions are [1, 5] and [5, 1].

翻译中…

For second query: $*n* = 7, *f* = 2$. Possible partitions are [1, 6] and [2, 5] and [3, 4] and [4, 3] and [5, 3] and [6, 1]. So in total there are 6 possible ways of partitioning.

翻译中…

样例

Input #1
5
6 2
7 2
6 3
6 4
7 4
Output #1
2
6
9
10
20
InputCopy OutputCopy
题目信息
题号
439E
时间限制
5 s
内存限制
256 MB
标签
组合数学
动态规划
数学

题面与样例版权归 Codeforces 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。