In article <> in rec.puzzles, Pete Mitchell <> wrote:

OBPuzzle: A "ship" starts at some unknown point on an integral Cartesian grid (x,y : both integers). It chooses one of the four directions (up, down, left, right), and each "turn" moves one in that direction (thus forming a ray of sorts, albeit of discrete points one unit apart). Each turn, starting with the time period before the ship moves, you can drop one bomb on one integer coordinate. To hit the ship, you must hit the exact coordinate that the ship is on at that turn. You don't know where the ship started, nor which of the four directions it chose. Given an infinite number of bombs, is it possible to *guarantee* that you will *eventually* hit the ship? If so, how; if not, why not?

To the solution; to the puzzles list; to the home page