The N Queens puzzle is the problem of placing eight chess queens on an n×n chessboard so that no two queens threaten each other. Thus, a solution requires that no two queens share the same row, column, or diagonal. The number of rotationally and reflectively distinct solutions for the first few N are 1, 0, 0, 2, 10, 4, 40, 92,... Example: The graphical demonstrations for the 8 queens problem: