winning strategy, first arrives 2021 wins Puerto Rico TST 2021.1
Source:
September 22, 2021
combinatoricsgamewinning strategy
Problem Statement
Ana and Beto are playing a game. Ana writes a whole number on the board. Beto then has the right to erase the number and add to it, or erase the number and subtract , as many times as he wants. Beto wins if he can get after a finite number of stages; otherwise, Ana wins. Which player has a winning strategy?