Flip rows, columns, not burgers
I heard a simple puzzle: starting with an all 0's nXn matrix, can you get any nXn target bit matrix using flip operations where each flip operation complements *each* element in a row or in a column. Trivially, this is not possible in general. Some of the other puzzles of this genre have operations where the sign of each row or column may be reversed, and the goal may be maximize the total sum of the numbers such as in Berlekamp's switching game (coding theory connection here). If anyone knows of novel puzzles of this genre, please let me know.