MathDB
Cutting rectangle game

Source: Kyiv City MO 2021 Round 1, Problem 7.2

December 21, 2023
gamecombinatoricscuttinggeometryrectangle

Problem Statement

Andriy and Olesya take turns (Andriy starts) in a 2×12 \times 1 rectangle, drawing horizontal segments of length 22 or vertical segments of length 11, as shown in the figure below.
https://i.ibb.co/qWqWxgh/Kyiv-MO-2021-Round-1-7-2.png
After each move, the value PP is calculated - the total perimeter of all small rectangles that are formed (i.e., those inside which no other segment passes). The winner is the one after whose move PP is divisible by 20212021 for the first time. Who has a winning strategy?
Proposed by Bogdan Rublov