IMO Shortlist 2012 problem C4
Kvaliteta:
Avg: 0,0Težina:
Avg: 7,0 Players
and
play a game with
coins and
boxes arranged around a circle. Initially
distributes the coins among the boxes so that there is at least
coin in each box. Then the two of them make moves in the order
by the following rules:
(a) On every move of his
passes
coin from every box to an adjacent box.
(b) On every move of hers
chooses several coins that were not involved in
's previous move and are in different boxes. She passes every coin to and adjacent box.
Player
's goal is to ensure at least
coin in each box after every move of hers, regardless of how
plays and how many moves are made. Find the least
that enables her to succeed.







(a) On every move of his


(b) On every move of hers


Player




Izvor: Međunarodna matematička olimpijada, shortlist 2012