bfs_undirected.cpp

/*For un-directed graph*/
#include<iostream>
#include<vector>
#include<queue>

#define MAX 100

using namespace std ; 

vector<int> adj[MAX] ; 
bool visited[MAX] ;
queue<int> q ;

void initialize(int  nodes){
	for (int i = 1; i<=nodes ;i++){
		visited[i] = false ;
	}
}

void bfs(int current){
	q.push(current) ;
	cout << current << "\t" ;
	visited[current]  = true ;
	while (!q.empty()){
		int v = q.front();
		q.pop() ;
	
		for(int i = 0; i<adj[v].size() ; i++){
			if (visited[adj[v][i]] == false){
				q.push(adj[v][i]);
				cout << adj[v][i] << "\t" ; 
				visited[adj[v][i]] = true ;
			}
		}
	}
}
int main ()
{
	int nodes , edges , i , x , y ; 
	cout  << "Enter the number of nodes\t" ; 
	cin >> nodes ; 
	cout << "Enter the total number of edges\t" ; 
	cin >> edges ; 

	cout <<"Enter the edges pairs of the graph (eg : a b , for a-b)\n";
	
	for (i = 0; i<edges ;i++){
		cin >> x >> y ; 
		adj[x].push_back(y) ; 
		adj[y].push_back(x) ;
	}

	initialize(nodes) ;
	
	cout << "Breadth first traversal\n";
	//for (int i = 1 ; i<=nodes ;i++){
		bfs(1) ;
	//}	
	
return 0 ; 
}