/*****************************************************************************

**

**    brute.cs

**

*****************************************************************************/

using System;

using System.Diagnostics;

class BruteForceSolver

    {

/*    -----------------------------------------------------------------------

    DECLARATIONS

    -----------------------------------------------------------------------    */

#region "DECLARATIONS"

#endregion

/*    -----------------------------------------------------------------------

    VARIABLES

    -----------------------------------------------------------------------    */

#region "VARIABLES"

    private int        _iSolutions;

    private Grid    _grid;

#endregion

/*    -----------------------------------------------------------------------

    STATIC METHODS

    -----------------------------------------------------------------------    */

#region "STATIC METHODS"

#endregion

/*    -----------------------------------------------------------------------

    CONSTRUCTOR

    -----------------------------------------------------------------------    */

#region "CONSTRUCTOR"

    ///

    ///    <summary>

    ///    Constructor for the "brute force solver" class

    ///    </summary>

    ///    

    public

    BruteForceSolver()

        {

        _grid = new Grid();

        _iSolutions = 0;

        }    /* end of BruteForceSolver::BruteForceSolver() */

#endregion        

/*    -----------------------------------------------------------------------

    PUBLIC METHODS

    -----------------------------------------------------------------------    */

#region "PUBLIC METHODS"

    ///

    /// <summary>

    /// Attempts to solve the puzzle

    /// </summary>

    /// <param name="grid">Grid to solve</param>

    /// <param name="bFindAll">TRUE to find all solutions, FALSE to stop after second</param>

    /// <param name="bListSolutions">TRUE to list all solutions</param>

    /// <returns>Number of solutions found</returns>

    /// 

    public int

    Solve( Grid grid, bool bFindAll, bool bListSolutions )

        {

        if (grid == null)

            return 0;

        _iSolutions = 0;

        _grid = (Grid) grid.Clone();

        search( !bFindAll, bListSolutions );

        return _iSolutions;

        }

    ///

    /// <summary>

    /// Recursive search

    /// </summary>

    /// <param name="bQuick">TRUE to stop after second solution</param>

    /// <param name="bListSolutions">TRUE to list all solutions</param>

    ///

    private void

    search( bool bQuick, bool bListSolutions )

        {

        if (_grid.EmptyCount == 0)

            {

//            Console.WriteLine( _grid.DisplayShortForm('.'));

            _iSolutions++;

            return;

            }

        //

        //    Find the square with the fewest candidates

        //

        int        iCount;

        int        iBest = Grid.BadIndex;

        int        iMinCount = Grid.Size + 1;

        for (int index = 0; index < Grid.Squares; ++index)

            {

            if (_grid[index].IsEmpty &&

                (iCount = _grid[index].CandidateCount) < iMinCount)

                {

                if (iCount == 0)

                    return;    // impossible puzzle

                iMinCount = iCount;

                iBest = index;

                }

            }

        //

        //    Now try all of the values in the best square, one at a time

        //

        if (Grid.IsValidIndex(iBest))

            {

            for (int iValue = Grid.ValueMin; iValue <= Grid.ValueMax; ++iValue)

                {

                if (_grid[iBest].Candidates.Test(iValue))

                    {

                    try

                        {

                        if (_grid.Set(iBest, iValue))

                            search(bQuick, bListSolutions);

                        }

                    catch (Exception)

                        { /* DO NOTHING */ }

                    if (bQuick && _iSolutions > 1)

                        return;

                    _grid.SetEmpty(iBest);

                    }

                }

            }

        }    /* end of BruteForceSolver::solve() */

#endregion

/*    -----------------------------------------------------------------------

    PROPERTIES

    -----------------------------------------------------------------------    */

#region "PROPERTIES"

    public int

    Solutions

        {

        get

            {

            return _iSolutions;

            }

        }

    }

#endregion

/*****************************************************************************

**

**    End of dlx.cs

**

*****************************************************************************/