program project1;

uses
  math;

type
  DblDyneVec = array of double;

  procedure Exchange(var a, b: Double);
var
  tmp: Double;
begin
  tmp := a;
  a := b;
  b := tmp;
end;


procedure QuickSortOn(X: DblDyneVec; Y: DblDyneVec = nil; Z: DblDyneVec = nil);

  procedure DoQuickSort(L, R: Integer);
  var
    I,J: Integer;
    P: Integer;
  begin
    repeat
      I := L;
      J := R;
      P := (L + R) div 2;
      repeat
        while CompareValue(X[P], X[I]) > 0 do inc(I);
        while CompareValue(X[P], X[J]) < 0 do dec(J);
        if I <= J then begin
          if I <> J then begin
            Exchange(X[I], X[J]);
            if Y <> nil then
              Exchange(Y[I], Y[J]);
            if Z <> nil then
              Exchange(Z[I], Z[J]);
          end;

          if P = I then
            P := J
          else if P = J then
            P := I;

          inc(I);
          dec(J);
        end;
      until I > J;

      if L < J then
        DoQuickSort(L, J);

      L := I;
    until I >= R;
  end;

begin
  DoQuickSort(0, High(X));
end;


var
  x: DblDyneVec;
  y: DblDyneVec;
  i: Integer;
begin
  SetLength(x, 10);
  SetLength(y, 10);

  for i := 0 to High(x) do
  begin
    x[i] := Random(100);
    y[i] := i;
  end;

  for i := 0 to High(x) do
    WriteLn('i: x=', x[i]:0:0, ' y=', y[i]:0:0);
  WriteLn;

  QuickSortOn(X, Y);

  for i := 0 to High(x) do
    WriteLn(i, ': x=', x[i]:0:0, ' y=', y[i]:0:0);

  ReadLn;
end.