What is the minimum number of strokes to reproduce the drawing below without lifting up the pencil from the paper (no tricks at all), and without passing over a line segment (or part of it) already drawn? You may begin and end wherever you like, and line segments may cross each other, but only as intersections.

Note: a new stroke occurs when a line type ceased because you have to stop and change direction.

(In reply to re(14): No Subject | spoiler | by Mindrod)

One definition of a stroke is "a single unbroken movement" (so one could argue that bringing the pen to paper is a stroke, but I won't) I would say that the solution is made from a single line but in fifteen strokes. Pcbouhid seams to be counting corners but it's his puzzle so thats fine. To fit the answer of "fifteen" in with the wording you just need to count the stroke bringing the pen down to the paper as the zero line type. A line is not necessarily a stroke but can be if it has no corners. A stroke is a line or a line segment depending on conditions.

Posted by Percy on 2005-11-25 16:33:24