C++ Programming Code Examples
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C++ Program to Check whether Undirected Graph is Connected using DFS
/* C++ Program to Check whether Undirected Graph is Connected using DFS */
#include <iostream>
#include <list>
#include <stack>
using namespace std;
/* Class Declaration */
class Graph
{
private:
int V;
list<int> *adj;
void DFSUtil(int v, bool visited[]);
public:
Graph(int V)
{
this->V = V;
adj = new list<int>[V];
}
~Graph()
{
delete [] adj;
}
void addEdge(int v, int w);
bool isConnected();
Graph getTranspose();
};
/* A recursive function to print DFS starting from v */
void Graph::DFSUtil(int v, bool visited[])
{
visited[v] = true;
list<int>::iterator i;
for (i = adj[v].begin(); i != adj[v].end(); ++i)
if (!visited[*i])
DFSUtil(*i, visited);
}
/* Function that returns reverse (or transpose) of this graph */
Graph Graph::getTranspose()
{
Graph g(V);
for (int v = 0; v < V; v++)
{
list<int>::iterator i;
for(i = adj[v].begin(); i != adj[v].end(); ++i)
{
g.adj[*i].push_back(v);
}
}
return g;
}
/* Add Edge to connect v and w */
void Graph::addEdge(int v, int w)
{
adj[v].push_back(w);
adj[w].push_back(v);
}
/* Check if Graph is Connected */
bool Graph::isConnected()
{
bool visited[V];
for (int i = 0; i < V; i++)
visited[i] = false;
DFSUtil(0, visited);
for (int i = 0; i < V; i++)
if (visited[i] == false)
return false;
Graph gr = getTranspose();
for(int i = 0; i < V; i++)
visited[i] = false;
gr.DFSUtil(0, visited);
for (int i = 0; i < V; i++)
if (visited[i] == false)
return false;
return true;
}
/* Main Contains Menu */
int main()
{
Graph g1(5);
g1.addEdge(0, 1);
g1.addEdge(1, 2);
g1.addEdge(2, 3);
g1.addEdge(3, 0);
g1.addEdge(2, 4);
g1.addEdge(4, 2);
if (g1.isConnected())
cout<<"The Graph is Conneted"<<endl;
else
cout<<"The Graph is not Connected"<<endl;
Graph g2(4);
g2.addEdge(0, 1);
g2.addEdge(1, 2);
g2.addEdge(2, 3);
if (g2.isConnected())
cout<<"The Graph is Connected"<<endl;
else
cout<<"The Graph is not Connected"<<endl;
return 0;
}
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