2024 Portuguese MO Day 2 P6
Source: 2024 Portuguese MO Day 2 P6
March 24, 2024
Game Theorycombinatorics
Problem Statement
Alexandre and Bernado are playing the following game. At the beginning, there are balls in a bag. At first turn, Alexandre can take one ball from the bag; at second turn, Bernado can take one or two balls from the bag, and so on. So they take turns and in turn, they can take a number of balls from to . Wins the one who makes the bag empty. For each value of , find who has the winning strategy.