304909: CF932E. Team Work
Memory Limit:256 MB
Time Limit:2 S
Judge Style:Text Compare
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Description
Team Work
题意翻译
给定 $ n,k $,求: $$ \sum_{i=1}^n\binom n i \times i^k $$ $ 1 \leq k \leq 5000,1 \leq n \leq 10^9 $题目描述
You have a team of $ N $ people. For a particular task, you can pick any non-empty subset of people. The cost of having $ x $ people for the task is $ x^{k} $ . Output the sum of costs over all non-empty subsets of people.输入输出格式
输入格式
Only line of input contains two integers $ N $ $ (1<=N<=10^{9}) $ representing total number of people and $ k $ $ (1<=k<=5000) $ .
输出格式
Output the sum of costs for all non empty subsets modulo $ 10^{9}+7 $ .
输入输出样例
输入样例 #1
1 1
输出样例 #1
1
输入样例 #2
3 2
输出样例 #2
24