Hi,

I have found an implementation for dijkstras algorithm on the internet and was wondering if someone could help me understand how the code works.

Many thanks

 private int nr_points=0;
 private int[][]Cost;
 private int []mask;

 private void dijkstraTSP()
   {
    if(nr_points==0)return;
    //algorithm=new String("Dijkstra");

    nod1=new Vector(); 
    nod2=new Vector();
    weight=new Vector();
    mask=new int[nr_points];
    //initialise mask with zeros (mask[x]=1 means the vertex is marked as used)
    for(int i=0;i<nr_points;i++)mask[i]=0;
    //Dijkstra:
    int []dd=new int[nr_points];
    int []pre=new int[nr_points];
    int []path=new int[nr_points+1];
    int init_vert=0,pos_in_path=0,new_vert=0;

    //initialise the vectors
    for(int i=0;i<nr_points;i++)
    {
       dd[i]=Cost[init_vert][i];
       pre[i]=init_vert;
       path[i]=-1;
    }
    pre[init_vert]=0;
    path[0]=init_vert;
    pos_in_path++;
    mask[init_vert]=1;

    for(int k=0;k<nr_points-1;k++)
    {
        //find min. cost in dd
        for(int j=0;j<nr_points;j++)
           if(dd[j]!=0 && mask[j]==0){new_vert=j; break;}

        for(int j=0;j<nr_points;j++)
           if(dd[j]<dd[new_vert] && mask[j]==0 && dd[j]!=0)new_vert=j;

        mask[new_vert]=1;
        path[pos_in_path]=new_vert;
        pos_in_path++;
        for(int j=0;j<nr_points;j++)
        {
           if(mask[j]==0)
           {
              if(dd[j]>dd[new_vert]+Cost[new_vert][j])
              {
                 dd[j]=dd[new_vert]+Cost[new_vert][j];
              }
           }
        }
    }
    //Close the cycle
    path[nr_points]=init_vert;

    //Save the solution in 3 vectors (for graphical purposes)
    for(int i=0;i<nr_points;i++)
    {
       nod1.addElement(path[i]);
       nod2.addElement(path[i+1]);
       weight.addElement(Cost[path[i]][path[i+1]]);
    }            
}