jahtzee · April 27, 2020 12:58
diff --git a/Representing rotatable two-dimensional structures with 1d arrays b/Representing rotatable two-dimensional structures with 1d arrays
 Representing rotatable two-dimensional structures with 1d arrays

       x
    0  1  2  3
    _ _ _ _ _ _ 
  0|0  1  2  3
 y 1|4  5  6  7
  2|8  9  10 11
  3|12 13 14 15

 i = index
 w = width

 0°) i=wy + x
 90°) i=w(w-1) + y - wx
 180°) i= w^2 - 1 - wy - x
 270°) i= w - 1 - y +wx
	Representing rotatable two-dimensional structures with 1d arrays

	x
	0 1 2 3
	_ _ _ _ _ _
	0\|0 1 2 3
	y 1\|4 5 6 7
	2\|8 9 10 11
	3\|12 13 14 15

	i = index
	w = width

	0°) i=wy + x
	90°) i=w(w-1) + y - wx
	180°) i= w^2 - 1 - wy - x
	270°) i= w - 1 - y +wx