This is a
solution to
problem 2 on the
hard interview questions node. If you have not read the
question, the
following will make no
sense to you:
Player 1 has a strategy to win. His first move is to put a quarter in the exact center of the table. If this is enough of a hint for you, I suggest you stop reading now. If you're just dying to know the rest, read on:
Player 2 then places a quarter anywhere on the table (but not in the center, of course). Now convince yourself that Player 1 always has a legal move: by playing a quarter diametrically opposite from the quarter Player 2 just put down (i.e., Player 1's first quarter is the midpoint of the line between Player 2's last quarter and Player 1's last quarter). We continue until we fill up the table, but since Player 1 always has a legal move, it is only Player 2 that will be faced with no legal move. Then Player 1 wins.
Note that this strategy works even in the degenerate case when the table is the size of a quarter.