一个简单的快速排序法

升序

procedure QuickSort(var arr: array of Integer; const left, right: Integer);

  procedure swap(const i, j: Integer);
  var
    vT: Integer;
  begin
    if i = j then Exit;
    vT := arr[i];
    arr[i] := arr[j];
    arr[j] := vT;
  end;

var
  vL, vR: Integer;
begin
  if left >= right then Exit;
  vL := left;
  vR := right + 1;
  while True do
  begin
    while vL + 1 < Length(arr) do
    begin
      Inc(vL);
      if arr[vL] >= arr[left] then Break;
    end;
    while vR - 1 < Length(arr) do
    begin
      Dec(vR);
      if arr[vR] <= arr[left] then Break;
    end;
    if vL >= vR then Break;
    swap(vL, vR);
  end;
  swap(left, vR);
  QuickSort(arr, left, vR - 1);
  QuickSort(arr, vR + 1, right);
end;

procedure TForm1.FormCreate(Sender: TObject);
var
  vA: array of Integer;
  vStr: string;
  i: Integer;
begin
  SetLength(vA, 10);
  vA[0] := 41;
  vA[1] := 24;
  vA[2] := 76;
  vA[3] := 11;
  vA[4] := 45;
  vA[5] := 64;
  vA[6] := 21;
  vA[7] := 69;
  vA[8] := 19;
  vA[9] := 36;
  QuickSort(vA, 0, Length(vA) - 1);
  for i := 0 to Length(vA) - 1 do
    vStr := vStr + ' ' + IntToStr(vA[i]);
  edt1.Text := vStr;
end;