Little Artem and Graph
题目描述
Little Artem is given a graph, constructed as follows: start with some k-clique, then add new vertices one by one, connecting them to k already existing vertices that form a k-clique.
Artem wants to count the number of spanning trees in this graph modulo 109+7.
First line of the input contains two integers n and k (1≤n≤10000, 1≤k≤min(n,5))− the total size of the graph and the size of the initial clique, respectively.
Next n-k lines describe k+1-th, k+2-th, ..., i-th, ..., n-th vertices by listing k distinct vertex indices 1≤aij<i it is connected to. It is guaranteed that those vertices form a k-clique.
Output a single integer− the number of spanning trees in the given graph modulo 109+7.
3 2
1 2
3
4 3
1 2 3
16
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