/// <summary>
/// Initializes an instance with the specified grid.
/// </summary>
/// <param name="grid">The grid.</param>
public BugChecker(IReadOnlyGrid grid)
{
if (grid.IsValid(out _))
{
(_emptyMap, _bivalueMap, _candMaps, _) = Grid = grid;
}
else
{
throw new ArgumentException(
"The specified grid does not have a unique solution.", nameof(grid));
}
}
/// <summary>
/// To check if the puzzle is diamond or not.
/// </summary>
/// <param name="this">(<see langword="this"/> parameter) The puzzle to check.</param>
/// <returns>A <see cref="bool"/> value indicating that.</returns>
public static bool IsDiamond(this IReadOnlyGrid @this)
{
// Using a faster solver to check the grid is unique or not.
if (@this.IsValid(out _))
{
var result = new ManualSolver().Solve(@this);
var(er, pr, dr) = (result.MaxDifficulty, result.PearlDifficulty, result.DiamondDifficulty);
return(er == pr && er == dr);
}
else
{
// The puzzle does not have unique solution, neither pearl nor diamond one.
return(false);
}
}
/// <summary>
/// Search all backdoors whose level is lower or equals than the
/// specified depth.
/// </summary>
/// <param name="grid">The grid.</param>
/// <param name="depth">
/// The depth you want to search for. The depth value must be between 0 and 3.
/// where value 0 is for searching for assignments.
/// </param>
/// <returns>All backdoors.</returns>
/// <exception cref="SudokuRuntimeException">
/// Throws when the specified grid is invalid.
/// </exception>
public IEnumerable <IReadOnlyList <Conclusion> > SearchForBackdoors(IReadOnlyGrid grid, int depth)
{
if (depth < 0 || depth > 3)
{
return(Array.Empty <IReadOnlyList <Conclusion> >());
}
if (!grid.IsValid(out _))
{
throw new SudokuRuntimeException();
}
var result = new List <IReadOnlyList <Conclusion> >();
for (int dep = 0; dep <= depth; dep++)
{
SearchForBackdoors(result, grid, dep);
}
return(result);
}
/// <summary> /// To check whether the puzzle can be solved using only simple sudoku technique set. /// </summary> /// <param name="this">(<see langword="this"/> parameter) The puzzle.</param> /// <returns>A <see cref="bool"/> value indicating that.</returns> public static bool CanBeSolvedUsingOnlySsts(this IReadOnlyGrid @this) => @this.IsValid(out _) ? new ManualSolver().Solve(@this).DifficultyLevel <= DifficultyLevel.Advanced : false;