MathDB
Spy Family Game

Source: 2024 Taiwan TST Round 1 Independent Study 1-C

March 6, 2024
Taiwancombinatorics

Problem Statement

Let n5n \geq 5 be a positive integer. There are nn stars with values 11 to nn, respectively. Anya and Becky play a game. Before the game starts, Anya places the nn stars in a row in whatever order she wishes. Then, starting from Becky, each player takes the left-most or right-most star in the row. After all the stars have been taken, the player with the highest total value of stars wins; if their total values are the same, then the game ends in a draw. Find all nn such that Becky has a winning strategy.
Proposed by Ho-Chien Chen