Program rotate square matrix by 90 degrees

{ matica_otoc.pas           Copyright (c) TrSek alias Zdeno Sekerak  }
{ Program otoci stvorcovu maticu o 90 stupnov.                       }
{                                                                    }
{ Datum:23.03.2016                              http://www.trsek.com }
program matica_otoc;
var mat: array[1..20,1..20] of integer;
    rozmer: integer;
    x,y: integer;
    zal: integer;
 
begin
  writeln('Program otoci stvorcovu maticu o 90 stupnov.');
  write('Zadaj rozmer matice = ');
  readln(rozmer);
 
  { nacita maticu }
  for y:=1 to rozmer do
   for x:=1 to rozmer do
    begin
      write('mat[',x,',',y,']=');
      readln(mat[x,y]);
    end;
 
   { otoci maticu }
   for y:=1 to rozmer div 2 do begin
    for x:=y to rozmer-y do begin
      { zaloha }
      zal:=mat[x,y];
 
      { vymena v kruhu }
      mat[x,y] := mat[y,rozmer-x+1];
      mat[y,rozmer-x+1] := mat[rozmer-x+1,rozmer-y+1];
      mat[rozmer-x+1,rozmer-y+1] := mat[rozmer-y+1,x];
      mat[rozmer-y+1,x] := zal;
    end;
   end;
 
 
  { vypise maticu }
  writeln('Matica otocena o 90 stupnov');
  for y:=1 to rozmer do
    for x:=1 to rozmer do
    begin
     if(x=1)then write('|');
     { vypise cislo }
     write(mat[x,y]:2);
     if(x<>rozmer)then write(', ');
     if(x= rozmer)then writeln('|');
    end;
 
  { pocka na enter }
  readln;
end.