Create dfs.cpp

Graphs/dfs.cpp

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+
+// C++ program to print DFS traversal from
+// a given vertex in a  given graph
+#include <bits/stdc++.h>
+using namespace std;
+
+// Graph class represents a directed graph
+// using adjacency list representation
+class Graph {
+public:
+    map<int, bool> visited;
+    map<int, list<int> > adj;
+
+    // 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);
+};
+
+void Graph::addEdge(int v, int w)
+{
+    adj[v].push_back(w); // Add w to v’s list.
+}
+
+void Graph::DFS(int v)
+{
+    // 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])
+            DFS(*i);
+}
+
+// Driver's code
+int main()
+{
+    // Create a graph given in the above diagram
+    Graph g;
+    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";
+
+    // Function call
+    g.DFS(2);
+
+    return 0;
+}