Tags down


Find all reachable vertices in a Boost BGL graph efficiently

By : haha
Date : October 14 2020, 02:15 PM
I hope this helps you . I'm new to boost graph library and trying to solve the following problem: ,
Use a filtered_graph and just use BFS or DFS to traverse?
code :

Share : facebook icon twitter icon

Python - Graph Data Structure - How Do I Implement Breadth-First Search to Find Reachable Vertices Correctly

By : user3058430
Date : March 29 2020, 07:55 AM
I hope this helps . Your code is way too complicated.
Start with a code just implementing the fundamentals and add features gradually. In order to get you started I'll post something simple but fundamental when handling graphs.
code :
from collections import deque

class fringe(object):
    def __init__(self, kind= 'stack'):
        f= deque()
        self._p= f.append if kind is 'stack' else f.appendleft
        self._f= f

    def __call__(self, item):
        return self

    def __iter__(self):
        while len(self._f):
            item= self._f.pop()
            yield item

    def __repr__(self):
        return self._f.__repr__().replace('deque', 'fringe')

def paths(G, start, terminal, F= fringe()):
    for node, path in F((start, [start])):
        for node in G[node]:
            if node is terminal:
                yield path+ [terminal]
            elif node not in path:
                F((node, path+ [node]))
if __name__ == '__main__':
    a, b, c, d, e, f= 'A', 'B', 'C', 'D', 'E', 'F'
    G= {a: [b, c], b: [c, d], c: [d], d: [c], e: [f], f: [c]}
    print 'All paths from:', a, 'to:', d
    print 'BFS'
    for path in paths(G, a, d): print path
    print 'DFS'
    for path in paths(G, a, d, fringe('queue')): print path
All paths from: A to: D
['A', 'C', 'D']
['A', 'B', 'D']
['A', 'B', 'C', 'D']
['A', 'B', 'D']
['A', 'C', 'D']
['A', 'B', 'C', 'D']

find the minimum number of vertices in a directed graph from which the other vertices are reachable

By : Bomber Saichan
Date : March 29 2020, 07:55 AM
will be helpful for those in need For the graph without cycle(i.e acyclic graph), it will be easy. All the nodes without incoming edges will be an optimal solution. Since all other nodes should be reachable from one of the nodes.
For the graph with cycle, find strongly connected component first, then you get a acyclic graph. The method above works again.

vertex or set of vertices reachable from all other vertices in a directed graph

By : user2711220
Date : March 29 2020, 07:55 AM
this one helps. Given a directed graph how to find vertex(call it "special vertex") that can be reached from all other vertices? It is not necessary that other vertices have to be reachable from this special vertex. , I would assume the graph is acyclic (i.e. a DAG)

Find all reachable vertices in a Boost BGL graph using BFS

By : Vlad
Date : March 29 2020, 07:55 AM
will be helpful for those in need The docs say that the Buffer needs to be a queue of vertex_descriptors. You accidentally declared it to have vertex_t (the vertex property bundle) as the value type.
Fix it:
code :
using vertex_descriptor = boost::graph_traits<Graph_t>::vertex_descriptor;

boost::queue<vertex_descriptor> Q;
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/breadth_first_search.hpp>
#include <variant>
#include <queue>

struct node_t {
struct specialNode_t {
enum class TerminalType {

using vertex_t = std::variant<node_t, specialNode_t>; // structs
using edge_t = std::variant<TerminalType>;            // enum

using Graph_t = boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, vertex_t, edge_t>;

int main() {
    Graph_t myGraph(5);
    boost::default_bfs_visitor vis; // Will do my collecting visitor later...

    auto indexmap = boost::get(boost::vertex_index, myGraph);
    auto colormap = boost::make_vector_property_map<boost::default_color_type>(indexmap);

    using vertex_descriptor = boost::graph_traits<Graph_t>::vertex_descriptor;

    boost::queue<vertex_descriptor> Q;
    boost::breadth_first_visit(myGraph, 0, Q, vis, colormap);

Find all vertices reachable from a vertex of a directed graph in time O(|E| + |V|)

By : Than Oo
Date : March 29 2020, 07:55 AM
will be helpful for those in need If you perform only one step of the DFS then it is O(1 + outdegree(v)), nevertheless, that will only get you the vertices that are reachable from v at one step, but not all the vertices that you may reach.
Think of the recursion, in order to retrieve all reachable vertices you should perform another recursive DFS search for each reached vertex. In the worst case you will reach all vertices and thus you will have the sum of O(1+outdegree(v)) for each vertex, so you will traverse all the edges of the graph and get O(|V|+|E|).
Related Posts Related Posts :
  • Template function broken after compiling with C++11
  • Is there a data race on packaged task arguments?
  • Malloc of pointer to an array- C++
  • Changing audio stream from physical input
  • Sorting a Vector of a custom class with std::sort() causes a segmentation fault
  • fastest way to read the last line of a string?
  • std::num_put issue with nan-boxing due to auto-cast from float to double
  • Difficulty with map's find function
  • Visual C++ executable will not run without Boost DLLs
  • #include <mutex> causes the bind() function call to throw errors at compile time, why?
  • Random_shuffle alternative in C++Builder6
  • C++ unique_ptr initialization
  • Is it really safe not to check in the copy assignemt operator whether an object is assigned to itself?
  • How to avoid passing param to template instantiation of reference-based helper class
  • c++ program not printing 2d vector grid properly but is close
  • Why isn't my array incrementing properly?
  • How to create your own Function for Async operation in c++ UWP?
  • C++ accessing a variable in a union struct
  • What does a implicitly defined destructor do
  • Member was not declared in base class template
  • Overloading << sign follow by a boolean expression
  • looser throw specifier for virtual function : GCC 4.9 complains but MSVC
  • Why does decltype(auto) not work as expected?
  • How to print and read at in the same line in Haskell?
  • SFINAE with Templated class Member functions
  • how to declare char * with input of {"data": "0001"}'
  • c++ program compile with LAPACK library
  • Enum in C++ Classes
  • Sort Specific Column of 2D int array (C++)
  • Unordered_map find const wchar_t*
  • OK to use these two parameters each independently, but fail to have both
  • Two classes with same, standalone, hidden functionality
  • C++: Instantiate object with no namespace
  • qml set text property from c++
  • Confused Backtrace of GDB while analysing core dump file at ../stdlib/strtod_l.c:734
  • syscall.MustLoadDll.MustFindProc throws "The specified procedure could not be found"
  • Why does structured binding not work as expected on struct?
  • Using lambda expression as Compare for std::set, when it's inside a vector
  • C++ Can't reference key of the map
  • Generic QuickSort implemented with vector and iterators C++
  • purpose for wait_for function in condition variable - C++11
  • Can I fill a template parameter with a nested class in this class?
  • Inconsistency parsing numeric literals according to C++ Standard's grammar
  • Array with fixed size at runtime
  • Which is better to check if a character exists in a std::string? find or find_first_of?
  • Insert element (TinyXml)
  • My argv[] in main always returns 0 when converted to integer
  • Indirect Path to Files, when program is called from somewhere else
  • Paint context and tool in maya for custom blendshape
  • shadow
    Privacy Policy - Terms - Contact Us © voile276.org