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2021 AMC 10B Question 24

AMC10 · 2021 AMC 10B

Question 24

Arjun and Beth play a game in which they take turns removing one brick or two adjacent bricks from one “wall” among a set of several walls of bricks, with gaps possibly creating new walls. The walls are one brick tall. For example, a set of walls of sizes $4$ and $2$ can be changed into any of the following by one move: $(3,2),$ $(2,1,2),$ $(4),$ $(4,1),$ $(2,2),$ or $(1,1,2).$

Question illustration

Arjun plays first, and the player who removes the last brick wins. For which starting configuration is there a strategy that guarantees a win for Beth?
  1. $ (6,1,1) $
  2. $ (6,2,1) $
  3. $ (6,2,2) $
  4. $ (6,3,1) $
  5. $ (6,3,2) $