Mirror Sudoku. Symmetry Sudoku. 400 Hardest sudoku

Symmetry – A Sudoku can have seven types of overall symmetry in its clue positions. They include:

90° rotational symmetry.

180° rotational symmetry.

reflection symmetry on one orthogonal axis.

reflection symmetry on two orthogonal axes.

reflection symmetry on one diagonal axis.

reflection symmetry on two diagonal axes.

dihedral symmetry.

A Sudoku (i.e. the. puzzle) is a partially completed grid. A grid has 9 rows, 9 columns and 9 boxes, each having 9 cells (81 total). Boxes can also be called blocks or regions. Horizontally adjacent rows are a band, and vertically adjacent columns are a stack. The initially defined values are clues or givens. An ordinary Sudoku (i.e. a proper Sudoku) has one solution. Rows, columns and regions can be collectively referred to as groups, of which the grid has 27. The One Rule encapsulates the three prime rules, i.e. each digit (or number) can occur only once in each row, column, and box; and can be compactly stated as: "Each digit appears once in each group."

400 Hardest symmetry sudoku puzzle - Mirror sudoku puzzle