IMC 2012 · Problem 3

Day 119th IMC · Blagoevgrad, Bulgaria

Statement

Given an integer n>1n > 1, let SnS_n be the group of permutations of the numbers 1,2,,n1, 2, \dots, n. Two players, AA and BB, play the following game. Taking turns, they select elements (one element at a time) from the group SnS_n. It is forbidden to select an element that has already been selected. The game ends when the selected elements generate the whole group SnS_n. The player who made the last move loses the game. The first move is made by AA. Which player has a winning strategy?

Official solution

Hidden so you can work on the problem first.

Proposed by Fedor Petrov, St. Petersburg State University.