Implemented Kosaraju's algorithm for getting Strongly Connencted Componenets.

Author: prince776

DataStructures/Graphs/strongly_connected_componenets.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+
+class Graph
+{
+	int V;
+	vector<int> *adj;
+
+	void fillOrder(int v, bool visited[], stack<int> &s);
+
+	void dfsUtil(int v, bool visited[]);
+
+public:
+	Graph(int V) : V(V)
+	{
+		adj = new vector<int>[V];
+	}
+	~Graph()
+	{
+		delete[] adj;
+	}
+
+	void addEdge(int v, int w);
+
+	void printSCCs();
+
+	Graph getTranspose();
+};
+
+void Graph::dfsUtil(int v, bool visited[])
+{
+	visited[v] = true;
+	cout << v <<  " ";
+	for (auto &it : adj[v])
+		if (!visited[it])
+			dfsUtil(it, visited);
+}
+
+Graph Graph::getTranspose()
+{
+	Graph g(V);
+	for (int i = 0; i < V; i++)
+	{
+		for (auto &it : adj[i])
+			g.adj[it].push_back(i);
+	}
+	return g;
+}
+
+void Graph::addEdge(int v, int w)
+{
+	adj[v].push_back(w);
+}
+
+void Graph::fillOrder(int v, bool visited[], stack<int> &s)
+{
+	visited[v] = true;
+	for (auto &it : adj[v])
+		if (!visited[it])
+			fillOrder(it, visited, s);
+	s.push(v);
+}
+
+void Graph::printSCCs()
+{
+	stack<int> s;
+	bool visited[V] = {0};
+	for (int i = 0; i < V; i++)
+		if (!visited[i])
+			fillOrder(i, visited, s);
+
+	Graph gr = getTranspose();
+	for (int i = 0; i < V; i++)
+		visited[i] = false;
+
+	while (!s.empty())
+	{
+		int v = s.top();
+		s.pop();
+		if (!visited[v])
+		{
+			gr.dfsUtil(v, visited);
+			cout << "\n";
+		}
+	}
+}
+
+int main()
+{
+	Graph g(5);
+	g.addEdge(1, 0);
+	g.addEdge(0, 2);
+	g.addEdge(2, 1);
+	g.addEdge(0, 3);
+	g.addEdge(3, 4);
+
+	cout << "Strongly Connected Components are:\n";
+	g.printSCCs();
+
+	return 0;
+}