Vitanuova for 2003 November 7

Annalee

I got to see Annalee for the first time since she got back from her year at MIT. Welcome back, Annalee!

Riddles

I really like William Wu's riddle site. A lot of the riddles are classics (things you might find in Gardner or Dudeney) and a lot are really straight CS problems, but the whole is full of great stuff. I enjoyed figuring out "Sink the Sub":

An enemy submarine is somewhere on the number line (consider only integers for this problem). It is moving at some rate (again, integral units per minute). You know neither its position nor its velocity.

You can launch a torpedo each minute at any integer on the number line. If the the submarine is there, you hit it and it sinks. You have all the time and torpedoes you want. You must sink this enemy sub - devise a strategy that is guaranteed to eventually hit the enemy sub.