题目描述
Problem Description
A permutation of length $ N $ is a rearrangement of $ N $ integers $ (1, 2, ..., N) $.
For a permutation $ A $ of length $ N $, the inversion number of $ A $ is the number of pairs $ (i, j) $ ($1 \leq i < j \leq N$) such that $ A_i > A_j $.
Find the number of permutations of length $ N $ such that the remainder when the inversion number is divided by $ K $ is $ m $, modulo $ 10^9+7 $.
Input Format
$ N $ $ K $ $ m $
Output Format
Output the number of permutations of length $ N $ such that the remainder when the inversion number is divided by $ K $ is $ m $, modulo $ 10^9+7 $.
Sample Input and Output
Sample Input #1
3 10 2
Sample Output #1
2
Sample Input #2
7 9 1
Sample Output #2
599
Sample Input #3
100 1 0
Sample Output #3
437918130
Notes/Hints
Constraints
- $1 \leq N \leq 10^{18}$
- $0 \leq m < K \leq 10$
Sample Explanation 1
The inversion number of a permutation of length $ 3 $ is at most $ 3 $, so in this case, we count the permutations with an inversion number of $ 2 $. The permutations with an inversion number of $ 2 $ are $ (3, 1, 2) $ and $ (2, 3, 1) $, which are $ 2 $ in total.
Sample Explanation 3
Output the result modulo $ 10^9+7 $.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分