Summary: Dual-connected components & strongly connected components & cut points & cut edge

Summary:

Various DFS timestamps .. All Tarjan (or his friends) worships Tarjan orzzzzzzzzz infinitely.

Tips and notes:

The strongly connected component is a directed graph, and the dual connected component is an undirected graph.

The decision for finding a ring for strongly connected components is very similar to that for dual-connected components, but not exactly the same.

The else if of the strongly connected component after if (FF [v]) must also determine whether it is in the stack, that is, vis [v], and then update ll [u].

Because the cut point and strongly connected component are undirected graphs, we need to determine a fa. We can maintain a fa parameter in DFS.

If the splitting component is required, the number of cut points + 1 for the Child tree of the node.

The splitting point does not require stack maintenance, but it is necessary to judge whether the current node is root (that is, when the node is child = 1 and is root, this point is not a splitting point ), instead of determining the root node, you can directly maintain the BCC in ll [v]> = FF [u.

Cut Edge is actually a special case of cut edge, that is, ll [u]> FF [u ..

Edge-Dual-connected components are better than vertices, that is, to find all the rings without edge cutting after the edge is cut, DFS.

Example of a cut point: [poj] 1523 SPF (cut point) (note the Special Command root)

Example of the double-connected component: [poj] 2942 knights of the Round Table (double-connected component) (do not forget that the stack is added in two if)

 

Summary: Dual-connected components & strongly connected components & cut points & cut edge