MathDB
TOT 487 1996 Spring J O5 2player game on 10x10 chessboard

Source:

July 9, 2024
combinatorics

Problem Statement

A game is played between two players on a 10×1010 \times 10 checkerboard. They move alternately, the first player marking XXs on vacant cells and the second OOs. When all 100100 cells have been marked, they calculate two numbers CC and ZZ. CC is the total number of five consecutive XXs in a row, a column or a diagonal, so that 66 consecutive XXs contribute a count of 22 to CC, 77 consecutive XXs contribute 33, and so on. Similarly, ZZ is the total number of five consecutive Os. The first player wins if C>ZC > Z, loses if C<ZC < Z and draws if C=ZC = Z. Does the first player have a strategy which guarantees (a) a draw or a win (b) a win regardless of the counter-strategy of the second player?
(A Belov)