1013: 湖南省第十七届大学生计算机程序设计竞赛（HNCPC2021） - Semilive
开始时间Start Time
比赛类型Contest Type
2021-12-05 18:00:00
结束时间End Time
2021-12-05 23:00:00
当前时间Current Time
2025-12-14 19:52:10
比赛状态Contest Status
公开Public
榜单状态Rank Status
D (1160) : Sum Them
时间限制Time Limit
1
秒Sec
内存限制Memory Limit
128
兆MB
提交次数Submitted
130
次Times
通过次数Solved
34
次Times
标准评测Standard Judge
题目描述Description
Given n and m, calculate the sum of the incremental multiplication formulas:
$$ f(n, m)=\sum_{i=1}^{n}\prod_{j=i}^{i+m-1}j $$
输入格式Input
No more than 50 test cases. Each case one line, including integer n and m.
1 ≤ n, m ≤ 106.
输出格式Output
For each test case, output the result of f(n, m) modulo 109 + 7.