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2011 Japan Mathematical Olympiad Finals Problem 3

Source: Japanese MO Finals 2011

February 11, 2011
algorithmcombinatorics proposedcombinatorics

Problem Statement

Person AA writes down non negative integers in each NN grid running in a line horizontally. When AA says one non negative integer, Person BB replaces some number in NN grid by the number that AA said. Repeat this procedure, when these numbers are arranged in the order of monotone increasing in the wider sense, the procedure is over. Is it possible that BB can finish in regard less of AA?