Games::Sudoku::General 0.007

Games::Sudoku::General is a Perl module that can solve sudoku-like puzzles.

SYNOPSIS

$su = Games::Sudoku::General->new ();
print $su->problem(<<eod)->solution();
3 . . . . 8 . 2 .
. . . . . 9 . . .
. . 2 7 . 5 . . .
2 4 . 5 . . 8 . .
. 8 5 . 7 4 . . 6
. 3 . . . . 9 4 .
1 . 4 . . . . 7 2
. . 6 9 . . . 5 .
. 7 . 6 1 2 . . 9
eod

This package solves puzzles that involve the allocation of symbols among a number of sets, such that no set contains more than one of any symbol. This class of problem includes the puzzles known as Sudoku, Number Place, and Wasabi.
Each Sudoku puzzle is considered to be made up of a number of cells, each of which is a member of one or more sets, and each of which may contain exactly one symbol. The contents of some of the cells are given, and the problem is to deduce the contents of the rest of the cells.

Although such puzzles as Sudoku are presented on a square grid, this package does not assume any particular geometry. Instead, the topology of the puzzle is defined by the user in terms of a list of the sets to which each cell belongs. Some topology generators are provided, but the user has the option of hand-specifying an arbitrary topology.

Even on the standard 9 x 9 Sudoku topology there are variants in which unspecified cells are constrained in various ways (odd/even, high/low). Such variants are accommodated by defining named sets of allowed symbols, and then giving the set name for each unoccupied cell to which it applies. See allowed_symbols for more information and an example.

This module is able not only to solve a variety of Sudoku-like puzzles, but to explain how it arrived at its solution. The steps() method, called after a solution is generated, lists in order what solution constraints were applied, what cell each constraint is applied to, and what symbol the cell was constrained to.