dijkstra algorithm

[johnkurtz]

Hey, could anybody lend me dijkstra's algorithm in pascal? (commented please). I have searched for it on Internet and I haven't find it.

Thanks.

[Duoas]

Nonsense.

[johnkurtz]

Sorry guys. I was too selfish.
I have tried to implement Dijkstra's algorithm. The next code gives me a problem with the procedure "print". In the while, "I" never takes the value of "parfirst" and I don't know what to do to solve the problem.

program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

  type
  matrix=array[1..5,1..5]of integer;
  tedge=record
  a,b:integer;
  c:integer;
  end;
  matrix1=array[1..5]of integer;

  var
  edges:array[1..5] of tedge;
  weight:matrix;      {matrix for the weight of each edge}
  weightmax,first,last:integer;  {infinity}
  distance:matrix1;  {distances between the first a node and each vertex}
  node:matrix1;  {previous vertex list}


   procedure inicialize (var paredges:array of tedge;var parweight:matrix;var parfirst,parlast:integer);
   var
   I,J:integer;

   begin
   paredges[1].a:=1;
   paredges[1].b:=2;
   paredges[1].c:=3;
   paredges[2].a:=2;
   paredges[2].b:=3;
   paredges[2].c:=5;
   paredges[3].a:=3;
   paredges[3].b:=4;
   paredges[3].c:=6;
   paredges[4].a:=1;
   paredges[4].b:=5;
   paredges[4].c:=5;
   paredges[5].a:=5;
   paredges[5].b:=4;
   paredges[5].c:=4;

   weightmax:=1;

   for I:=1 to 5 do weightmax:=weightmax + paredges[I].c;

   for I:=1 to 5 do
   for J:=1 to 5 do
   parweight[I,J]:=weightmax;

   parweight[1,2]:=3;
   parweight[2,1]:=3;
   parweight[2,3]:=5;
   parweight[3,2]:=5;
   parweight[3,4]:=6;
   parweight[4,3]:=6;
   parweight[4,5]:=4;
   parweight[5,4]:=4;
   parweight[1,5]:=5;
   parweight[5,1]:=5;

   writeln;
   write('First node: ');
   readln(parfirst);
   write('Last node: ');
   readln(parlast);
   end;


   procedure calculate(parweight:matrix; var pardistance, parnode:array of integer;weightmax,parfirst,parlast:integer);
   var
   I,K,S,J,dist,Dmin,Kmin:integer;
   nodebis:array[1..5]of integer;

   begin
   for I:=1 to 5 do begin
   parnode[I]:=0;
   pardistance[I]:=weightmax;
   end;

   {for now, only the first node is in the list}
   parnode[parfirst]:=parfirst;
   pardistance[parfirst]:=0;
   S:=1;
   nodebis[1]:=parfirst;

   repeat
   {new i: minimun distance}
   Kmin:=S;
   I:=nodebis[S];
   Dmin:=pardistance[I];

   for K:=1 to S-1 do begin
   J:=nodebis[K];
   Dist:=pardistance[J];

   if (Dist<Dmin) then begin
   Kmin:=K;
   I:=J;
   Dmin:=Dist;
   end;
   end;

   if (I<>last) then begin
   nodebis[Kmin]:=nodebis[S];
   S:=S-1;
               {see other nodes around i}
   for J:=1 to 5 do
   if (pardistance[I] + parweight[I,J]<pardistance[J])then begin
   if (pardistance[J]=weightmax) then begin
   S:=S+1;          {add j to the list}
   nodebis[S]:=J;
   end;
            {update}
   pardistance[J]:=pardistance[I]+parweight[I,J];
   parnode[J]:=I;
   end;
   end;
   until (I=parlast) or (S=0);
   end;


   procedure print(parnode:array of integer;parfirst,parlast:integer);
   var
   I,path:integer;
   pathnode:array[1..5]of integer;

   begin
   path:=1;
   pathnode[1]:=parlast;
   I:=parlast;

   while(I<>parfirst) do begin  {print the nodes turning them}
   I:=parnode[I];
   path:=path+1;
   pathnode[path]:=I;
   end;

   writeln;
   writeln('The nodes of the shortest path: ');
   For I:=path downto 1 do begin
   write(pathnode[I]);
   end;
   end;

begin

   inicialize(edges,weight,first,last);
   calculate(weight,distance,node,weightmax,first,last);
   print(node,first,last);
   readln;
end.

[luis_ramos]

Not repeat the use of i, j , that cause the error

[luis_ramos]

Not repeat the use of i, j , that cause the error