IMO 2023 Shortlist C2
Determine the maximal length L of a sequence a1,...,aL of positive integers satisfying both the following properties: • ...
Category: Combinatorics
Problem
Determine the maximal length L of a sequence a1,...,aL of positive integers satisfying
both the following properties:
• every term in the sequence is less than or equal to 22023
, and
• there does not exist a consecutive subsequence ai,ai1,...,aj (where 1 ď i ď j ď L) with a choice of signs si,si1,...,sj P t1,´1u for which
siai si1ai1 ¨¨¨ ` sjaj “ 0.
(Czech Republic)