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GRiddles Series C: Puzzle 3
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Laser focus
A laser beam enters a (2n − 1) × (2n − 1) grid, n ⩾ 3, horizontally at the middle cell of the left wall, where a mirror has already been placed, as shown on Figure 1. Ana paints n of the outer edges of the grid green. Then Bob and Ana take turns, Bob first, each placing one
two-sided mirror at 45° in an empty cell.
After each of Bob’s turns Ana scores a point if the beam points at an edge she has painted. Figure 2 shows a turn on which she does not score a point.
Ana wins if she scores a point three times in a row. Does Ana have a winning strategy?
Answer format: Determine whether Ana has a winning strategy and prove it.
Submit your answer here!
Please note that only your first submission will be considered.
