Given a simple graph, output the number of simple cycles in it. A simple cycle is a cycle with no repeated vertices or edges.
输入描述:
The first line of input contains two integers n and m (1 ≤ n ≤ 19, 0 ≤ m) – respectively the number of vertices and edges of the graph. Each of the subsequent m lines contains two integers a and b, (1 ≤ a, b ≤ n, a ≠ b) indicating that vertices a and b are connected by an undirected edge. There is no more than one edge connecting any pair of vertices.
输出描述:
Output the number of cycles in the given graph.
示例1
输入
4 6<br />1 2<br />1 3<br />1 4<br />2 3<br />2 4<br />3 4<br />
备注:
The example graph is a clique and contains four cycles of length 3 and three cycles of length 4.
加载中...