6548: Random
内存限制：64 MB
时间限制：1.000 S
评测方式：文本比较
命题人：
提交：41
解决：6
题目描述
N numbers, randomly generated between [0,1]
Make M operation, 1/2 probability to delete the maximum value, 1/2 probability to delete the minimum value
Calculate the sum of expected value module 109+7
Make M operation, 1/2 probability to delete the maximum value, 1/2 probability to delete the minimum value
Calculate the sum of expected value module 109+7
输入
Each test contains multiple test cases. The first line contains the number of test cases T (1≤T≤10000). Description of the test cases follows.
The first line of each test case contains two integers n,m
1≤m≤n≤109
The first line of each test case contains two integers n,m
1≤m≤n≤109
输出
For each test case, print one integer — the answer to the problem.
样例输入 复制
2
2 2
3 1样例输出 复制
0
1