使用BGL（Boost图形库）查找DAG中的所有拓扑排序

Question

How can use the Boost Graph Library to find all the topological sorts of a given DAG G ?

I have found some theoretical references explaining that is possible, there's also this code where there's an implementation. But I don't actually want to start from scratch, and I want to use BGL to compute them.

Answer 1

One strategy would be to get all vertices without predecessors (no directed edges to it). And multiplying vectors based on vertices without predecessors. If you have a C++ to do it please share.

The code to get depth_first topological sort:

Given a DAG graph with vertex type vertex_t :

deque<vertex_t> topologicalSorted;

//perform topological sort
if (topologicalSort(graph, topologicalSorted)) {
    cout << "The graph is directed acyclic!" << endl;
    cout << "Topological order: ";
    for (int i = 0; i < topologicalSorted.size(); i++) {
        cout << graph[topologicalSorted.at(i)].label << " ";
    }
    cout << endl;
} 


bool topologicalSort()
{
    try
    {
        boost::topological_sort(graph, front_inserter(topologicalSorted));
    }
    catch (boost::not_a_dag)
    {
        cout << "not a dag\n";
        return false;
    }
    cout << "top sort OK\n";

    return true;
} 

Without custom vertex:

deque<int> topologicalSorted;

if (topologicalSort()) {
        // Print the results.
        for (int i = 0; i < topologicalSorted.size(); i++) {
            cout << topologicalSorted.at(i) << ",";
        }
        cout << endl;
    }