CF1777B.Emordnilap
普及/提高-
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题目描述
A permutation of length n is an array consisting of n distinct integers from 1 to n in arbitrary order. For example, [2,3,1,5,4] is a permutation, but [1,2,2] is not a permutation ( 2 appears twice in the array), and [1,3,4] is also not a permutation ( n=3 but there is 4 in the array). There are n!=n⋅(n−1)⋅(n−2)⋅…⋅1 different permutations of length n .
Given a permutation p of n numbers, we create an array a consisting of 2n numbers, which is equal to p concatenated with its reverse. We then define the beauty of p as the number of inversions in a .
The number of inversions in the array a is the number of pairs of indices i , j such that i<j and ai>aj .
For example, for permutation p=[1,2] , a would be [1,2,2,1] . The inversions in a are (2,4) and (3,4) (assuming 1-based indexing). Hence, the beauty of p is 2 .
Your task is to find the sum of beauties of all n! permutations of size n . Print the remainder we get when dividing this value by 1000000007 ( 109+7 ).
输入格式
Each test contains multiple test cases. The first line contains the number of test cases t ( 1≤t≤105 ). The description of the test cases follows.
Each test case has only one line — the integer n ( 1≤n≤105 ).
It is guaranteed that the sum of n over all test cases does not exceed 105 .
输出格式
For each test case, print one integer — the sum of beauties of all permutations of size n modulo 1000000007 ( 109+7 ).
输入输出样例
输入#1
3 1 2 100
输出#1
0 4 389456655
说明/提示
For the first test case of the example, p=[1] is the only permutation. a=[1,1] has 0 inversions.
For the second test case of the example, the permutations are [1,2] and [2,1] . Their respective a arrays are [1,2,2,1] and [2,1,1,2] , both of which have 2 inversions.