Algoritma discrap

#include <cstdlib>
#include <iostream>
#define MAX 20
#define INFINITY 9999

using namespace std;
class dijkstra
{
      private:
      int n;
      int graph[MAX][MAX];
      int colour[MAX];
      int start;
      int distance[MAX];
      int predecessor[MAX];
      enum {green,yellow,red};
public:
       void read_graph();
       void initialize();
       int select_min_distance_lable();
       void update(int);
       void output();
       void function();

};
void dijkstra::read_graph()
{
     cout<<"Enter the no. of nodes in the graph ::";
     cin>>n;
     cout<<"Enter the adjacency matrix for the graph ::\n";
     int i,j;
     for(i=1;i<=n;i++)
     for(j=1;j<=n;j++)
     cin>>graph[i][j];
     for(i=1;i<=n;i++)
     colour[i]=green;
     cout<<"Enter the start vertex ::";
     cin>>start;
}
void dijkstra::initialize()
{
     for(int i=1;i<=n;i++)
{
     if(i==start)
     distance[i]=0;
     else
     distance[i]=INFINITY;
}
     for(int j=1;j<=n;j++)
{
     if(graph[start][j]!=0)
     predecessor[j]=start;
else
    predecessor[j]=0;
}
}
    int dijkstra::select_min_distance_lable()

{
    int min=INFINITY;
    int p=0;
    for(int i=1;i<=n;i++)
{
            if(colour[i]==green)
{
            if(min>=distance[i])
{
            min=distance[i];
            p=i;
}
}
}
return p;
}
         void dijkstra::update(int p) // p is a yellow colour node
{
         cout<<"\nupdated distances are ::\n";
         for(int i=1;i<=n;i++)
{
         if(colour[i]==green)
{
         if(graph[p][i]!=0)
{
         if(distance[i]>graph[p][i]+distance[p])
{
         distance[i]=graph[p][i]+distance[p];
         predecessor[i]=p;
}
}
}
         cout<<distance[i]<<'\t';
}
}
void dijkstra::output()

{
                       cout<<"****** The final paths and the distacnes are ******\n\n";
                       for(int i=1;i<=n;i++)
{
                       if(predecessor[i]==0 && i!=start)
{
                       cout<<"path does not exists between "<<i<<" and thestart vertex "<<start<<endl;
                       exit(1);
}
          cout<<"path for node “<<i<<” is ::\n";
          int j=i;
          int array[MAX];
          int l=0;
          while(predecessor[j]!=0)
{
          array[++l]=predecessor[j];
          j=predecessor[j];
}
          for(int k=l;k>=1;k=-k)
          cout<<array[k]<<"->";
          cout<<i<<endl;
          cout<<"distance is "<<distance[i]<<endl<<endl<<endl;
}
}
void dijkstra::function()
{
              cout<<"\n**********************************************************************\n";
              cout<<"This program is to implement dijkstra’s algorithm using colourcodes \n";
              cout<<"**********************************************************************\n\n";
              read_graph();
              initialize();
//repeate until all nodes become red
          int flag=0;
          int i;
             cout<<"\n\n******** The working of the algorithm is **********\n\n";
             for(i=1;i<=n;i++)
             if(colour[i]!=red)
             flag=1;
             cout<<"The initial distances are ::\n";
             for(i=1;i<=n;i++)
             cout<<distance[i]<<'\t';
             cout<<endl;
             while(flag)
{
             int p=select_min_distance_lable();
             cout<<"\nThe min distance lable that is coloured yellow is "<<p;
             colour[p]=yellow;
             update(p);
             cout<<"\nnode "<<p<<" is coloured red "<<endl;
             colour[p]=red;
             flag=0;
             for(i=1;i<=n;i++)
             if(colour[i]!=red)
             flag=1;
             cout<<endl<<endl<<endl;
}
             output();
}
int main(int argc, char *argv[])
{   dijkstra d;
    d.function();

    system("PAUSE");
    return EXIT_SUCCESS;
}