func solve(s *domain.Sudoku) error {
// Always print the final sudoku before exiting
defer s.Print()
// Apply the cages combinations read from the data file
if err := strategies.KillerCombinations(s); err != nil {
return err
}
// List of strategies we can apply, ordered from simpler and quicker to
// more complex and slower
slist := []Strategy{
strategies.HiddenSingles,
strategies.NakedPairs,
}
for {
// Check if the puzzle is solved
if s.Solved() {
return nil
}
// Check for solved squares
if done, err := s.SolvedSquares(); err != nil {
return err
} else if done {
continue
}
// Apply all the strategies to the sudoku
// until one modifies the content
i := 0
for _, strat := range slist {
i += 1
if done, err := strat(s); err != nil {
return err
} else if done {
i -= 1
break
}
}
// The puzzle can't be solved
if i == len(slist) {
break
}
}
fmt.Println("ERROR: No more strategies to try. Puzzle unsolvable")
return nil
//return domain.NewErrorf("no more strategies to try. puzzle unsolvable")
}
