Vertex Cover Problem

// Program to print Vertex Cover of a given undirected graph 
#include<iostream> 
#include <list> 
using namespace std; 

// This class represents a undirected graph using adjacency list 
class Graph 
{ 
	int V; // No. of vertices 
	list<int> *adj; // Pointer to an array containing adjacency lists 
public: 
	Graph(int V); // Constructor 
	void addEdge(int v, int w); // function to add an edge to graph 
	void printVertexCover(); // prints vertex cover 
}; 

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. 
	adj[w].push_back(v); // Since the graph is undirected 
} 

// The function to print vertex cover 
void Graph::printVertexCover() 
{ 
	// Initialize all vertices as not visited. 
	bool visited[V]; 
	for (int i=0; i<V; i++) 
		visited[i] = false; 

	list<int>::iterator i; 

	// Consider all edges one by one 
	for (int u=0; u<V; u++) 
	{ 
		// An edge is only picked when both visited[u] and visited[v] 
		// are false 
		if (visited[u] == false) 
		{ 
			// Go through all adjacents of u and pick the first not 
			// yet visited vertex (We are basically picking an edge 
			// (u, v) from remaining edges. 
			for (i= adj[u].begin(); i != adj[u].end(); ++i) 
			{ 
				int v = *i; 
				if (visited[v] == false) 
				{ 
					// Add the vertices (u, v) to the result set. 
					// We make the vertex u and v visited so that 
					// all edges from/to them would be ignored 
					visited[v] = true; 
					visited[u] = true; 
					break; 
				} 
			} 
		} 
	} 

	// Print the vertex cover 
	for (int i=0; i<V; i++) 
		if (visited[i]) 
		cout << i << " "; 
} 

// Driver program to test methods of graph class 
int main() 
{ 
	// Create a graph given in the above diagram 
	Graph g(7); 
	g.addEdge(0, 1); 
	g.addEdge(0, 2); 
	g.addEdge(1, 3); 
	g.addEdge(3, 4); 
	g.addEdge(4, 5); 
	g.addEdge(5, 6); 

	g.printVertexCover(); 

	return 0; 
}