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In the standard form of this puzzle type, you are given a grid in which some squares contain a white circle or a black circle. You are to fill in white or black circles in the empty squares so that nowhere does a white circle have black circles both on its immediate left and right, or both immediately above and below. A single circle "alone" on the edge of the grid is allowed. In addition, each row and each column has exactly half its circles black and half white.
MIT Mystery Hunt 2015 Polyglot