Sat Apr 23 2022

tags: exploration puzzle public

Toh gave this puzzle to me and Wilfred in Gold Mine; coded this on Saturday afternoon with Rayhan before going to Croatia

One hundred ants are dropped on a meter stick. Each ant is traveling either to the left or the right with constant speed 1 meter per minute. When two ants meet, they bounce off each other and reverse direction. When an ant reaches an end of the stick, it falls off. At some point all the ants will have fallen off. The time at which this happens will depend on the initial configuration of the ants.


Over ALL possible initial configurations, what is the longest amount of time that you would need to wait to guarantee that the stick has no more ants?


One minute, regardless of the number of ants.

Proof by animation