program algoritma djikstra

#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<<"masukkan jumlah node = ";
     cin>>n;
     cout<<"masukkan nilai matrik untuk graf ::\n";
     int i,j;
     for(i=1;i<=n;i++){
                       for(j=1;j<=n;j++){
                                         cout<<"["<<i<<"],["<<j<<"]=";
                                         cin>>graph[i][j];}}
     for(i=1;i<=n;i++){
                       colour[i]=green;}
     cout<<"masukkan vertex mulai :: ";
     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){
     cout<<"\nupdate jarak = \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 the start 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--)
   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 colour codes* \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;
}