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Problem of the Week 1072
Sinister, Dexter, Sinister, Dexter
Consider a maze in the plane made from a network with a specified starting point S, which has a single edge leaving from it, and such that at each vertex (other than S) there are only two possible choices: turn left or turn right (a backwards move is not allowed).
True or False: If one makes alternating moves left, right, left, right, and so on, one always returns to S.
This diagram shows a case where one does return.
Source: Puzzle 17 at the Carnegie-Mellon University CS Puzzle Page.
© Copyright 2007 Stan Wagon. Reproduced with permission.