BreadthFirstSearch.cpp

#include<iostream> 
#include <list> 
using namespace std;
class Graph{ 
int V; list<int> *adj;
public: 
Graph(int V); void addEdge(int v, int w);

  void BFS(int s);
};
Graph::Graph(int V){
this->V = V; adj = new list<int>[V];
}

void Graph::addEdge(int v, int w){
adj[v].push_back(w);
}

void Graph::BFS(int s){
bool *visited = new bool[V]; for(int i = 0; i < V; i++)
visited[i] = false;
list<int> queue;
visited[s] = true; queue.push_back(s);
list<int>::iterator i;
while(!queue.empty()){
s = queue.front(); cout << s << " "; queue.pop_front();
for (i = adj[s].begin(); i != adj[s].end(); ++i){
  if (!visited[*i]){
    visited[*i] = true; queue.push_back(*i);
}
}
}
}
int main(){
Graph g(4);
g.addEdge(0, 1);
g.addEdge(0, 2);
g.addEdge(1, 2);
g.addEdge(2, 0);
g.addEdge(2, 3);
g.addEdge(3, 3);
cout << "Following is Breadth First Traversal "<<"(starting from vertex 2) \n";
g.BFS(2);
return 0;
}