source: tspsg/src/tspsolver.h @ 94cd045fad

/*!
 * \file tspsolver.h
 * \author Copyright &copy; 2007-2010 Lёppa <contacts[at]oleksii[dot]name>
 *
 *  $Id$
 *  $URL$
 *
 * \brief Defines TSPSolver namespace and everything needed for solving TSP tasks.
 *
 *  <b>TSPSG: TSP Solver and Generator</b>
 *
 *  This file is part of TSPSG.
 *
 *  TSPSG is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  TSPSG is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with TSPSG.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef TSPSOLVER_H
#define TSPSOLVER_H

#include <QtCore>
#include <limits>

/*!
 * \def INFINITY
 * \brief This value means infinity :-)
 *
 *  Some libraries already have \c INFINITY defined.
 *  We need to redefine it for the \c INFINITY to always have the same value.
 */
#ifdef INFINITY
        #undef INFINITY
#endif
#define INFINITY std::numeric_limits<double>::infinity()

/*!
 * \brief A TSP Solver namespace.
 *
 *  This namespace contains all the stuff required for solving TSP tasks.
 */
namespace TSPSolver {

//! A matrix of city-to-city travel costs
typedef QList<QList<double> > TMatrix;

/*!
 * \brief This structure represents one step of solving.
 *
 *  A tree of such elements will represent the solving process.
 */
struct SStep {
        //! A structure that represents a candidate for branching
        struct SCandidate {
                int nRow; //!< A zero-based row number of the candidate
                int nCol; //!< A zero-based column number of the candidate

                //! Assigns default values
                SCandidate() {
                        nCol = nRow = -1;
                }
                //! An operator == implementation
                bool operator ==(const SCandidate &cand) const {
                        return ((cand.nRow == nRow) && (cand.nCol == nCol));
                }
        };

        //! An enum that describes possible selection of the next step
        enum NextStep {
                NoNextStep, //!< No next step (end of solution)
                LeftBranch, //!< Left branch was selected for the next step
                RightBranch //!< Right branch was selected for the next step
        };

        TMatrix matrix; //!< This step's matrix
        double price; //!< The price of travel to this step

        SCandidate candidate; //!< A candiadate for branching in the current step
        QList<SCandidate> alts; //!< A list of alternative branching candidates
        SStep *pNode; //!< Pointer to the parent step
        SStep *plNode; //!< Pointer to the left branch step
        SStep *prNode; //!< Pointer to the right branch step
        NextStep next; //!< Indicates what branch was selected for the next step

        //! Assigns default values
        SStep() {
                price = -1;
                pNode = plNode = prNode = NULL;
                next = NoNextStep;
        }
};

/*!
 * \brief This class solves Travelling Salesman Problem task.
 * \author Copyright &copy; 2007-2010 Lёppa <contacts[at]oleksii[dot]name>
 */
class CTSPSolver: public QObject
{
        Q_OBJECT

public:
        static QString getVersionId();

        CTSPSolver(QObject *parent = NULL);
        void cleanup(bool processEvents = false);
        QString getSortedPath(const QString &city, const QString &separator = " -> ") const;
        int getTotalSteps() const;
        bool isOptimal() const;
        SStep *solve(int numCities, const TMatrix &task);
        bool wasCanceled() const;
        ~CTSPSolver();

public slots:
        void cancel();

signals:
        /*!
         * \brief This signal is emitted once every time a part of the route is found.
         * \param n Indicates the number of the route parts found.
         */
        void routePartFound(int n);

private:
        bool mayNotBeOptimal, canceled;
        int nCities, total;
        SStep *root;
        QHash<int,int> route;
        mutable QMutex mutex;

        double align(TMatrix &matrix);
        void deleteTree(SStep *&root, bool processEvents = false);
        void denormalize(TMatrix &matrix) const;
        QList<SStep::SCandidate> findCandidate(const TMatrix &matrix, int &nRow, int &nCol) const;
        double findMinInCol(int nCol, const TMatrix &matrix, int exr = -1) const;
        double findMinInRow(int nRow, const TMatrix &matrix, int exc = -1) const;
        void finishRoute();
        bool hasSubCycles(int nRow, int nCol) const;
        void normalize(TMatrix &matrix) const;
        void subCol(TMatrix &matrix, int nCol, double val);
        void subRow(TMatrix &matrix, int nRow, double val);
};

}

#ifdef DEBUG
QDebug operator<<(QDebug dbg, const TSPSolver::TMatrix &matrix);
QDebug operator<<(QDebug dbg, const TSPSolver::SStep::SCandidate &candidate);
#endif // DEBUG

#endif // TSPSOLVER_H