Graph - BFS

Program run Breadth First Search in Undirected Graph

Author: Rayden-prog

BFS in Graph

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+// Program to print BFS traversal from a given 
+// source vertex. BFS(int s) traverses vertices 
+// reachable from s. 
+#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; 
+}