Spiral matrix: Difference between revisions

=={{header|Delphi}}==

{{works with|Delphi|6.0}}

{{libheader|SysUtils,StdCtrls, Windows}}

This code actually creates a the required matrix instead of simulating one. It can also create matricies of any size and the matricies don't have to be square. It works by creating a rectangle of the same size as the matrix, then entering the values along the lines of the rectangle. It then uses the Windows library routine "InflateRect" to decrease the size of the rectangle until the whole matrix is filled with spiraling values.

<syntaxhighlight lang="Delphi">

type TMatrix = array of array of double;

procedure DisplayMatrix(Memo: TMemo; Mat: TMatrix);

{Display specified matrix}

var X,Y: integer;

var S: string;

begin

S:='';

for Y:=0 to High(Mat[0]) do

begin

S:=S+'[';

for X:=0 to High(Mat) do

S:=S+Format('%4.0f',[Mat[X,Y]]);

S:=S+']'+#$0D#$0A;

end;

Memo.Lines.Add(S);

end;

procedure MakeSpiralMatrix(var Mat: TMatrix; SizeX,SizeY: integer);

{Create a spiral matrix of specified size}

var Inx: integer;

var R: TRect;

procedure DoRect(R: TRect; var Inx: integer);

{Create on turn of the spiral base on the rectangle}

var X,Y: integer;

begin

{Do top part of rectangle}

for X:=R.Left to R.Right do

begin

Mat[X,R.Top]:=Inx;

Inc(Inx);

end;

{Do Right part of rectangle}

for Y:=R.Top+1 to R.Bottom do

begin

Mat[R.Right,Y]:=Inx;

Inc(Inx);

end;

{Do bottom part of rectangle}

for X:= R.Right-1 downto R.Left do

begin

Mat[X,R.Bottom]:=Inx;

Inc(Inx);

end;

{Do left part of rectangle}

for Y:=R.Bottom-1 downto R.Top+1 do

begin

Mat[R.Left,Y]:=Inx;

Inc(Inx);

end;

end;

begin

{Set matrix size}

SetLength(Mat,SizeX,SizeY);

{create matching rectangle}

R:=Rect(0,0,SizeX-1,SizeY-1);

Inx:=0;

{draw and deflate rectanle until spiral is done}

while (R.Left<=R.Right) and (R.Top<=R.Bottom) do

begin

DoRect(R,Inx);

InflateRect(R,-1,-1);

end;

end;

procedure SpiralMatrix(Memo: TMemo);

{Display spiral matrix}

var Mat: TMatrix;

begin

Memo.Lines.Add('5x5 Matrix');

MakeSpiralMatrix(Mat,5,5);

DisplayMatrix(Memo,Mat);

Memo.Lines.Add('8x8 Matrix');

MakeSpiralMatrix(Mat,8,8);

DisplayMatrix(Memo,Mat);

Memo.Lines.Add('14x8 Matrix');

MakeSpiralMatrix(Mat,14,8);

DisplayMatrix(Memo,Mat);

end;

</syntaxhighlight>

{{out}}

<pre>

5x5 Matrix

[ 0 1 2 3 4]

[ 15 16 17 18 5]

[ 14 23 24 19 6]

[ 13 22 21 20 7]

[ 12 11 10 9 8]

8x8 Matrix

[ 0 1 2 3 4 5 6 7]

[ 27 28 29 30 31 32 33 8]

[ 26 47 48 49 50 51 34 9]

[ 25 46 59 60 61 52 35 10]

[ 24 45 58 63 62 53 36 11]

[ 23 44 57 56 55 54 37 12]

[ 22 43 42 41 40 39 38 13]

[ 21 20 19 18 17 16 15 14]

14x8 Matrix

[ 0 1 2 3 4 5 6 7 8 9 10 11 12 13]

[ 39 40 41 42 43 44 45 46 47 48 49 50 51 14]

[ 38 71 72 73 74 75 76 77 78 79 80 81 52 15]

[ 37 70 95 96 97 98 99 100 101 102 103 82 53 16]

[ 36 69 94 111 110 109 108 107 106 105 104 83 54 17]

[ 35 68 93 92 91 90 89 88 87 86 85 84 55 18]

[ 34 67 66 65 64 63 62 61 60 59 58 57 56 19]

[ 33 32 31 30 29 28 27 26 25 24 23 22 21 20]

Elapsed Time: 11.242 ms.

</pre>