C++ Program to Find Strongly Connected Components in Graphs

Weakly or Strongly Connected for a given a directed graph can be found out using DFS. This is a C++ program of this problem.

Functions used

Begin
Function fillorder() = fill stack with all the vertices.
   a) Mark the current node as visited and print it
   b) Recur for all the vertices adjacent to this vertex
   c) All vertices reachable from v are processed by now, push v to Stack
End
Begin
Function DFS() :
   a) Mark the current node as visited and print it
   b) Recur for all the vertices adjacent to this vertex
End

Example

#include 
#include 
#include 
using namespace std;
class G {
   int m;
   list *adj;
   //declaration of functions
   void fillOrder(int n, bool visited[], stack &Stack);
   void DFS(int n, bool visited[]);
   public:
   G(int N); //constructor
   void addEd(int v, int w);
   int print();
   G getTranspose();
};
G::G(int m) {
   this->m = m;
   adj = new list [m];
}
void G::DFS(int n, bool visited[]) {
   visited[n] = true; // Mark the current node as visited and print it
   cout ::iterator i;
   //Recur for all the vertices adjacent to this vertex
   for (i = adj[n].begin(); i != adj[n].end(); ++i)
      if (!visited[*i])
         DFS(*i, visited);
}
G G::getTranspose() {
   G g(m);
   for (int n = 0; n::iterator i;
      for (i = adj[n].begin(); i != adj[n].end(); ++i) {
         g.adj[*i].push_back(n);
      }
   }
   return g;
}
void G::addEd(int v, int w) {
   adj[v].push_back(w); //add w to v's list
}
void G::fillOrder(int v, bool visited[], stack &Stack) {
   visited[v] = true; //Mark the current node as visited and print it
   list::iterator i;
   //Recur for all the vertices adjacent to this vertex
   for (i = adj[v].begin(); i != adj[v].end(); ++i)
      if (!visited[*i])
         fillOrder(*i, visited, Stack);
   Stack.push(v);
}
int G::print() { //print the solution
   stack Stack;
   bool *visited = new bool[m];
   for (int i = 0; i  1) {
      cout 
Output
Following are strongly connected components in given
graph
4
0 1 2 3
Graph is weakly connected.