C++ Program to Apply DFS to Perform the Topological Sorting of a Directed Acyclic Graph Full Project For Beginners

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main.cpp

 

 

// A C++ program to print topological sorting of a DAG
#include<iostream>
#include <list>
#include <stack>
using namespace std;
 
// Class to represent a graph
class Graph
{
        int V; // No. of vertices'
 
        // Pointer to an array containing adjacency listsList
        list<int> *adj;
 
        // A function used by topologicalSort
        void topologicalSortUtil(int v, bool visited[], stack<int> &Stack);
    public:
        Graph(int V); // Constructor
 
        // function to add an edge to graph
        void addEdge(int v, int w);
 
        // prints a Topological Sort of the complete graph
        void topologicalSort();
};
 
Graph::Graph(int V)
{
    this->V = V;
    adj = new list<int> [V];
}
 
void Graph::addEdge(int v, int w)
{
    adj[v].push_back(w); // Add w to v’s list.
}
 
// A recursive function used by topologicalSort
void Graph::topologicalSortUtil(int v, bool visited[], stack<int> &Stack)
{
    // Mark the current node as visited.
    visited[v] = true;
 
    // Recur for all the vertices adjacent to this vertex
    list<int>::iterator i;
    for (i = adj[v].begin(); i != adj[v].end(); ++i)
        if (!visited[*i])
            topologicalSortUtil(*i, visited, Stack);
 
    // Push current vertex to stack which stores result
    Stack.push(v);
}
 
// The function to do Topological Sort. It uses recursive topologicalSortUtil()
void Graph::topologicalSort()
{
    stack<int> Stack;
 
    // Mark all the vertices as not visited
    bool *visited = new bool[V];
    for (int i = 0; i < V; i++)
        visited[i] = false;
 
    // Call the recursive helper function to store Topological Sort
    // starting from all vertices one by one
    for (int i = 0; i < V; i++)
        if (visited[i] == false)
            topologicalSortUtil(i, visited, Stack);
 
    // Print contents of stack
    while (Stack.empty() == false)
    {
        cout << Stack.top() << " ";
        Stack.pop();
    }
}
 
// Driver program to test above functions
int main()
{
    // Create a graph given in the above diagram
    Graph g(6);
    g.addEdge(5, 2);
    g.addEdge(5, 0);
    g.addEdge(4, 0);
    g.addEdge(4, 1);
    g.addEdge(2, 3);
    g.addEdge(3, 1);
 
    cout << "Following is a Topological Sort of the given graph \n";
    g.topologicalSort();
 
    return 0;
}

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