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MathNet 2023-part-06 — 191 problems (EN–VI) Question 82

Math Olympiad Vault · MathNet 2023-part-06 — 191 problems (EN–VI)

Question 82

The wizards Albus and Brian are playing a game on a square of side length $2n+1$ metres surrounded by lava. In the centre of the square there sits a toad. In a turn, a wizard chooses a direction parallel to a side of the square and enchants the toad. This will cause the toad to jump $d$ metres in the chosen direction, where $d$ is initially equal to $1$ and increases by $1$ after each jump. The wizard who sends the toad into the lava loses. Albus begins and they take turns. Depending on $n$, determine which wizard has a winning strategy.