![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
#include
using namespace std;
// This class represents a directed graph using adjacency list representation
class Graph
{
int V; // No. of vertices
list *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[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](https://image.slidesharecdn.com/implementbreadth-firstsearchwithaqueuesolutionprogram-230705222855-84dfaf80/85/Implement-Breadth-First-Search-with-a-QueueSolution-Program-pdf-1-320.jpg)
![list 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::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);](https://image.slidesharecdn.com/implementbreadth-firstsearchwithaqueuesolutionprogram-230705222855-84dfaf80/85/Implement-Breadth-First-Search-with-a-QueueSolution-Program-pdf-2-320.jpg)
![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
#include
using namespace std;
// This class represents a directed graph using adjacency list representation
class Graph
{
int V; // No. of vertices
list *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[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];](https://image.slidesharecdn.com/implementbreadth-firstsearchwithaqueuesolutionprogram-230705222855-84dfaf80/85/Implement-Breadth-First-Search-with-a-QueueSolution-Program-pdf-3-320.jpg)
![for(int i = 0; i < V; i++)
visited[i] = false;
// Create a queue for BFS
list 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::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);](https://image.slidesharecdn.com/implementbreadth-firstsearchwithaqueuesolutionprogram-230705222855-84dfaf80/85/Implement-Breadth-First-Search-with-a-QueueSolution-Program-pdf-4-320.jpg)
Implement Breadth-First Search with a QueueSolution Program .pdf
- 1. 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 #include using namespace std; // This class represents a directed graph using adjacency list representation class Graph { int V; // No. of vertices list *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[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
- 2. list 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::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);
- 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 #include using namespace std; // This class represents a directed graph using adjacency list representation class Graph { int V; // No. of vertices list *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[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];
- 4. for(int i = 0; i < V; i++) visited[i] = false; // Create a queue for BFS list 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::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);
- 5. 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; }