MathDB
2 player game in 11x11 grid

Source: 2011 Swedish Mathematical Competition p5

May 1, 2021
combinatoricsgamegame strategywinning strategy

Problem Statement

Arne and Bertil play a game on an 11×1111 \times 11 grid. Arne starts. He has a game piece that is placed on the center od the grid at the beginning of the game. At each move he moves the piece one step horizontally or vertically. Bertil places a wall along each move any of an optional four squares. Arne is not allowed to move his piece through a wall. Arne wins if he manages to move the pice out of the board, while Bertil wins if he manages to prevent Arne from doing that. Who wins if from the beginning there are no walls on the game board and both players play optimally?