Merge c112fc9845 into ca3d16dcce

bfs

@@ -0,0 +1,92 @@
+#include<iostream> 
+#include <list> 
+  
+using namespace std; 
+  
+// This class represents a directed graph using 
+// adjacency list representation 
+class Graph 
+{ 
+    int V;    // No. of vertices 
+  
+    // Pointer to an array containing adjacency 
+    // lists 
+    list<int> *adj;    
+public: 
+    Graph(int V);  // Constructor 
+  
+    // function to add an edge to graph 
+    void addEdge(int v, int w);  
+  
+    // prints BFS traversal from a given source s 
+    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); // Add w to v’s list. 
+} 
+  
+void Graph::BFS(int s) 
+{ 
+    // Mark all the vertices as not visited 
+    bool *visited = new bool[V]; 
+    for(int i = 0; i < V; i++) 
+        visited[i] = false; 
+  
+    // Create a queue for BFS 
+    list<int> queue; 
+  
+    // Mark the current node as visited and enqueue it 
+    visited[s] = true; 
+    queue.push_back(s); 
+  
+    // 'i' will be used to get all adjacent 
+    // vertices of a vertex 
+    list<int>::iterator i; 
+  
+    while(!queue.empty()) 
+    { 
+        // Dequeue a vertex from queue and print it 
+        s = queue.front(); 
+        cout << s << " "; 
+        queue.pop_front(); 
+  
+        // Get all adjacent vertices of the dequeued 
+        // vertex s. If a adjacent has not been visited,  
+        // then mark it visited and enqueue it 
+        for (i = adj[s].begin(); i != adj[s].end(); ++i) 
+        { 
+            if (!visited[*i]) 
+            { 
+                visited[*i] = true; 
+                queue.push_back(*i); 
+            } 
+        } 
+    } 
+} 
+  
+// Driver program to test methods of graph class 
+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 Breadth First Traversal "
+         << "(starting from vertex 2) \n"; 
+    g.BFS(2); 
+  
+    return 0; 
+}