A submarine is travelling with constant speed on a one-dimensional grid. Its position at the end of every minute is always an integer and its velocity per minute is also an integer. You can specify a number for each minute and a missile will hit that number on the grid at the end of the minute.
Does there exist a strategy so that you are guaranteed to hit the vessel at some future time even though you don't know its position and velocity?
(I've worked out a "mathematical" solution but i'm interested to see if anyone has one that doesn't need the maths)