MathDB
2023 Fall LMT Team #10 distinct cells in a 4x4 grid

Source:

February 4, 2024
combinatorics

Problem Statement

Aidan and Andrew independently select distinct cells in a 44 by 44 grid, as well as a direction (either up, down, left, or right), both at random. Every second, each of them will travel 11 cell in their chosen direction. Find the probability that Aidan and Andrew willmeet (be in the same cell at the same time) before either one of them hits an edge of the grid. (If Aidan and Andrew cross paths by switching cells, it doesn’t count as meeting.)