Winning strategy: Prevent B from getting a square
Source: BWM 2013 P4
June 8, 2014
modular arithmeticquadraticsfloor functioncombinatorics proposedcombinatorics
Problem Statement
Two players and play the following game taking alternate moves. In each move, a player writes one digit on the blackboard. Each new digit is written either to the right or left of the sequence of digits already written on the blackboard. Suppose that begins the game and initially the blackboard was empty. wins the game if ,after some move of , the sequence of digits written in the blackboard represents a perfect square. Prove that can prevent from winning.