Homework SourseImplement BreadthFirst Search with a QueueSolution Program t
Implement Breadth-First Search with a Queue
Solution
// 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
list<int> *adj; // Pointer to an array containing adjacency lists
public:
Graph(int V); // Constructor
void addEdge(int v, int w); // function to add an edge to graph
void BFS(int s); // prints BFS traversal from a given source 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) \ \";
g.BFS(2);
return 0;
}
Output:
| // 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 list<int> *adj; // Pointer to an array containing adjacency lists public: Graph(int V); // Constructor void addEdge(int v, int w); // function to add an edge to graph void BFS(int s); // prints BFS traversal from a given source 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) \ \"; g.BFS(2); return 0; } |
