bfs.cpp

#include<iostream>

using namespace std;

int q[50], front = 0, rear = -1;

void insert_q(int ele)
{
    q[++rear] = ele;
}

int delete_q()
{
    if(front > rear) 
        return -1;
    return q[front++];
}

//Representation of the graph
int G[4][4]={   {0, 1, 0, 1},
                {1, 0, 1, 0},
                {0, 1, 0, 0},
                {1, 0, 0, 0}    };    

//Mark all nodes as unvisited
int visited[4] = {0,0,0,0};

void bfs(int v)
{
    //Mark current node as visited and display
    visited[v] = 1;
    cout<<v<<" ";

    //For each node
    for(int i = 0; i < 4; ++i)
        //Check if it is connected to current node and unvisited
        if( (G[v][i] == 1) && (visited[i] != 1) )
        {
            //Mark as visited and add to queue
            visited[i] = 1;
            insert_q(i);
        }

    int u;
    //BFS on each node in the queue
    while((u = delete_q()) != -1)
        bfs(u);
}                                

int main()
{
    bfs(0);            //Starting node to perform BFS
    return 0;
}