IMO Shortlist 2012 problem C1
Dodao/la: arhiva3. studenoga 2013.
Several positive integers are written in a row. Iteratively, Alice chooses two adjacent numbers
is to the left of
, and replaces the pair
. Prove that she can perform only finitely many such iterations.
Proposed by Warut Suksompong, Thailand
Izvor: Međunarodna matematička olimpijada, shortlist 2012