QOJ.ac

QOJ

Time Limit: 2 s Memory Limit: 256 MB Total points: 100 Hackable ✓

#2104. 因子统计

الإحصائيات

题目描述

你有 $q$ 组询问,每组询问你需要计算出组合数 $\binom{n}{m}$ 的因子数量。

$\binom{n}{m}$ 表示 $n$ 个互不相同的球中取 $m$ 个球的方案数,也就是

$$ \binom{n}{m} = \frac{n!}{m!(n-m)!} $$

由于答案可能很大,你只需要输出将答案对 $p = 10^9 + 7$ 取模的结果即可。

输入格式

从标准输入读入数据。

第一行一个正整数 $q$ 表示询问数量。

接下来 $q$ 行,每行 2 个整数 $n, m$,保证 $0\le m \le n$。

输入格式

输出到标准输出。

输出 $q$ 行,每行一个整数对应该询问的答案。

样例

输入

3
0 0
4 2
10 3

输出

1
4
16

解释

$\binom 0 0 = 1$,有 $1$ 个因子。

$\binom 4 2 = 6$,有 $4$ 个因子:$\{1, 2, 3, 6\}$。

$\binom {10} 3 = 120$,有 $16$ 个因子:$\{1,2,3,4,5,6,8,10,12,15,20,24,30,40,60,120\}$。

样例二

见下载目录下的 ex_divisor2.inex_divisor2.ans

子任务

对于 $100\%$ 的数据,保证 $q \le 10^{5}, n \le 10^{5}$

测试点$n$$q$特殊性质
$1$$\le 20$$=10^2$
$2$$=10^5$
$3,4$$\le 3,000$$=3,000$
$5$$\le 10^5$A
$6$$=10^5$
$7,8$B
$9,10$

特殊性质 A:保证 $\binom n m \le 10^6$。

特殊性质 B:保证输入的 $n$ 值总是同一个数。

时空限制:2s, 256MB

About Issues

We understand that our problem archive is not perfect. If you find any issues with the problem, including the statement, scoring configuration, time/memory limits, test cases, etc.

You may use this form to submit an issue regarding the problem. A problem moderator will review your issue and proceed it properly.

STOP! Before you submit an issue, please READ the following guidelines:

  1. This is not a place to publish a discussion, editorial, or requests to debug your code. Your issue will only be visible by you and problem moderators. Other users will not be able to view or reply your issues.
  2. Do not submit duplicated issues. If you have already submitted one, please wait for an moderator to review it. Submitting multiple issues will not speed up the review process and might cause your account to be banned.
  3. Issues must be filed in English or Chinese only.
  4. Be sure your issue is related to this problem. If you need to submit an issue regarding another problem, contest, category, etc., you should submit it to the corresponding page.

Active Issues 0

No issues in this category.

Closed/Resolved Issues 0

No issues in this category.