Created
January 3, 2017 15:09
-
-
Save zSANSANz/b22c487637249049a74b0cc04a393ba7 to your computer and use it in GitHub Desktop.
Breadth First Traversal for a Graph on C++
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// 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) \n"; | |
g.BFS(2); | |
return 0; | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment