Problem #PRU-78535

Problems Discrete Mathematics Algorithm Theory Game theory Game theory (other)

Problem

Two players play on a square field of size 99×99, which has been split onto cells of size 1×1. The first player places a cross on the center of the field; After this, the second player can place a zero on any of the eight cells surrounding the cross of the first player. After that, the first puts a cross onto any cell of the field next to one of those already occupied, etc. The first player wins if he can put a cross on any corner cell. Prove that with any strategy of the second player the first can always win.