BFS source code #1

Problem : First you have to store a graph in a adjacency list.Then you have to determine the shortest distance between source and destination node.

Problem link and solution idea : http://www.shafaetsplanet.com/planetcoding/?p=604

Source code :

#include<bits/stdc++.h>

using namespace std;

int main()
{
    cout<<"Eenter node and edge number : ";
    int node,edge;

    cin>>node>>edge;

    vector<int>v[100];

    int i;
    int a,b;
    cout<<"Enter nodes connecting edges : "<<endl;
    for(i=1; i<=edge; i++)
    {
        cin>>a>>b;
        v[a].push_back(b);
    }
    cout<<endl;
    int source,destination;

    while(1)
    {
        cout<<"Source : ";
        cin>>source;
        cout<<"destination : ";
        cin>>destination;

        int visited[100];

        memset(visited,-1,sizeof(visited));

        queue<int>q;

        q.push(source);

        visited[source]=0;

        int u,p;

        while(!q.empty())
        {
            u=q.front();
            q.pop();
            for(i=0; i<v[u].size(); i++)
            {
                p=v[u][i];

                if(visited[p]==-1)
                {
                    visited[p]=visited[u]+1;
                    q.push(p);
                    if(p==destination) break;
                }

            }
        }
        cout<<"Shortest distance betwwen destination and source : ";
        cout<<visited[destination]-visited[source]<<endl<<endl;

    }
    return 0;
}