depthfirstsearch.cpp

//dfs traversal for a given graph
#include<iostream> 
#include<list> 
using namespace std; 
  

class Graph 
{ 
    int V;  
  
    
    list<int> *adj; 
  
    // A recursive function used by DFS 
    void DFSUtil(int v, bool visited[]); 
public: 
    Graph(int V);   // Constructor 
  
    // function to add an edge to graph 
    void addEdge(int v, int w); 
  
    // DFS traversal of the vertices 
    // reachable from v 
    void DFS(int v); 
}; 
  
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. 
} 
  
void Graph::DFSUtil(int v, bool visited[]) 
{ 
    // Mark the current node as visited and 
    // print it 
    visited[v] = true; 
    cout << v << " "; 
  
    // 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]) 
            DFSUtil(*i, visited); 
} 
  
// DFS traversal of the vertices reachable from v. 
// It uses recursive DFSUtil() 
void Graph::DFS(int v) 
{ 
    // 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 print DFS traversal 
    DFSUtil(v, visited); 
} 
  
int main() 
{ 
    // Create a graph given in the above diagram 
    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 Depth First Traversal"
            " (starting from vertex 2) \n"; 
    g.DFS(2); 
  
    return 0; 
}