1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414
|
/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Mikael Lagerkvist <lagerkvist@gecode.org>
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Mikael Lagerkvist, 2008
* Christian Schulte, 2001
*
* Last modified:
* $Date: 2010-07-02 10:59:05 +0200 (Fri, 02 Jul 2010) $ by $Author: schulte $
* $Revision: 11148 $
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <gecode/driver.hh>
#include <gecode/int.hh>
#include <gecode/minimodel.hh>
#include <gecode/graph.hh>
#ifdef GECODE_HAS_GIST
#include <QtGui>
#endif
using namespace Gecode;
/** \brief Custom brancher for knight's tours using Warnsdorff's rule
*
* This class implements Warnsdorff's rule for finding knight's
* tours. The next position is choosen by taking the jump that
* minimizes the number of alternatives in the next step.
*
* \relates Knights
*/
class Warnsdorff : public Brancher {
protected:
/// Views of the brancher
ViewArray<Int::IntView> x;
/// Next variable to branch on
mutable int start;
/// %Choice
class Choice : public Gecode::Choice {
public:
/// Position of variable
int pos;
/// Value of variable
int val;
/** Initialize choice for brancher \a b, position \a pos0,
* and value \a val0.
*/
Choice(const Brancher& b, int pos0, int val0)
: Gecode::Choice(b,2), pos(pos0), val(val0) {}
/// Report size occupied
virtual size_t size(void) const {
return sizeof(Choice);
}
};
/// Construct brancher
Warnsdorff(Home home, ViewArray<Int::IntView>& xv)
: Brancher(home), x(xv), start(0) {}
/// Copy constructor
Warnsdorff(Space& home, bool share, Warnsdorff& b)
: Brancher(home, share, b), start(b.start) {
x.update(home, share, b.x);
}
public:
/// Check status of brancher, return true if alternatives left
virtual bool status(const Space&) const {
// A path to follow can be at most x.size() long
for (int n=x.size(); n--; ) {
if (!x[start].assigned())
return true;
// Follow path of assigned variables
start = x[start].val();
}
return false;
}
/// Return choice
virtual Gecode::Choice* choice(Space&) {
Int::ViewValues<Int::IntView> iv(x[start]);
int n = iv.val();
unsigned int min = x[n].size();
++iv;
// Choose the value with the fewest neighbors
while (iv()) {
if (x[iv.val()].size() < min) {
n = iv.val();
min = x[n].size();
}
++iv;
}
return new Choice(*this, start, n);
}
/// Perform commit for choice \a _c and alternative \a a
virtual ExecStatus commit(Space& home, const Gecode::Choice& _c,
unsigned int a) {
const Choice& c = static_cast<const Choice&>(_c);
if (a == 0)
return me_failed(x[c.pos].eq(home, c.val)) ? ES_FAILED : ES_OK;
else
return me_failed(x[c.pos].nq(home, c.val)) ? ES_FAILED : ES_OK;
}
/// Copy brancher
virtual Actor* copy(Space& home, bool share) {
return new (home) Warnsdorff(home, share, *this);
}
/// Post brancher
static void post(Home home, const IntVarArgs& x) {
ViewArray<Int::IntView> xv(home, x);
(void) new (home) Warnsdorff(home, xv);
}
/// Delete brancher and return its size
virtual size_t dispose(Space&) {
return sizeof(*this);
}
};
/// Base-class for knight's tour example
class Knights : public Script {
public:
/// Size of board
const int n;
/// Maps board field to successor field
IntVarArray succ;
/// Propagation to use for model
enum {
PROP_REIFIED, ///< Use reified constraints
PROP_CIRCUIT ///< Use single circuit constraints
};
/// Branching to use for model
enum {
BRANCH_NAIVE, ///< Use naive, lexicographical branching
BRANCH_WARNSDORFF, ///< Use Warnsdorff's rule
};
/// Return field at position \a x, \a y
int f(int x, int y) const {
return x + y*n;
}
/// Return x coordinate at field \a f
int x(int f) const {
return f % n;
}
/// Return y coordinate at field \a f
int y(int f) const {
return f / n;
}
/// Compute set of neighbour fields
IntSet neighbors(int i) {
static const int moves[8][2] = {
{-2,-1}, {-2,1}, {-1,-2}, {-1,2}, {1,-2}, {1,2}, {2,-1}, {2,1}
};
int nbs[8]; int n_nbs = 0;
for (int m=0; m<8; m++) {
int nx = x(i) + moves[m][0], ny = y(i) + moves[m][1];
if ((nx >= 0) && (nx < n) && (ny >= 0) && (ny < n))
nbs[n_nbs++] = f(nx,ny);
}
return IntSet(nbs,n_nbs);
}
/// Constructor
Knights(const SizeOptions& opt)
: n(opt.size()), succ(*this,n*n,0,n*n-1) {
switch (opt.branching()) {
case BRANCH_NAIVE:
branch(*this, succ, INT_VAR_NONE, INT_VAL_MIN);
break;
case BRANCH_WARNSDORFF:
Warnsdorff::post(*this, succ);
break;
}
}
/// Constructor for cloning \a s
Knights(bool share, Knights& s) : Script(share,s), n(s.n) {
succ.update(*this, share, s.succ);
}
/// Print board
virtual void
print(std::ostream& os) const {
int* jump = new int[n*n];
{
int j=0;
for (int i=0; i<n*n; i++) {
jump[j]=i; j=succ[j].min();
}
}
os << "\t";
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
os.width(3);
os << jump[f(i,j)] << " ";
}
os << std::endl << "\t";
}
os << std::endl;
delete [] jump;
}
};
/**
* \brief %Example: n-Knight's tour (simple model)
*
* Fill an n times n chess board with knight's moves such that
* the knight does a full tour (last move reaches first move
* again). The formulation is due to Gert Smolka.
*
* \ingroup ExProblem
*
*/
class KnightsReified : public Knights {
public:
KnightsReified(const SizeOptions& opt) : Knights(opt) {
const int nn = n*n;
// Map knight to its predecessor of succesor on board
IntVarArgs jump(nn);
IntVarArgs pred(nn);
for (int i = nn; i--; ) {
IntVar p(*this,0,nn-1); pred[i]=p;
IntVar j(*this,0,nn-1); jump[i]=j;
}
// Place the first two knights
rel(*this, jump[f(0,0)], IRT_EQ, 0);
rel(*this, jump[f(1,2)], IRT_EQ, 1);
distinct(*this, jump, opt.icl());
channel(*this, succ, pred, opt.icl());
for (int f = 0; f < nn; f++) {
IntSet ds = neighbors(f);
for (IntSetValues i(ds); i(); ++i)
rel(*this,
expr(*this, (jump[i.val()]-jump[f] == 1)),
BOT_XOR,
expr(*this, (jump[i.val()]-jump[f] == 1-nn)),
expr(*this, (succ[f] == i.val())));
dom(*this, pred[f], ds);
dom(*this, succ[f], ds);
rel(*this, succ[f], IRT_NQ, pred[f]);
}
}
/// Constructor for cloning \a s
KnightsReified(bool share, KnightsReified& s) : Knights(share,s) {}
/// Copy during cloning
virtual Space*
copy(bool share) {
return new KnightsReified(share,*this);
}
};
/**
* \brief %Example: n-%Knights tour (model using circuit)
*
* Fill an n times n chess board with knights such that the
* knights do a full tour by knights move (last knight reaches
* first knight again).
*
* \ingroup ExProblem
*
*/
class KnightsCircuit : public Knights {
public:
KnightsCircuit(const SizeOptions& opt) : Knights(opt) {
// Fix the first move
rel(*this, succ[0], IRT_EQ, f(1,2));
circuit(*this, succ, opt.icl());
for (int f = 0; f < n*n; f++)
dom(*this, succ[f], neighbors(f));
}
/// Constructor for cloning \a s
KnightsCircuit(bool share, KnightsCircuit& s) : Knights(share,s) {}
/// Copy during cloning
virtual Space*
copy(bool share) {
return new KnightsCircuit(share,*this);
}
};
#ifdef GECODE_HAS_GIST
/// Inspector showing knight moves on a chess board
class KnightsInspector : public Gist::Inspector {
protected:
/// The graphics scene displaying the board
QGraphicsScene* scene;
/// The window containing the graphics scene
QMainWindow* mw;
/// The size of a field on the board
static const int unit = 30;
public:
/// Constructor
KnightsInspector(void) : scene(NULL), mw(NULL) {}
/// Inspect space \a s
virtual void inspect(const Space& s) {
const Knights& k = static_cast<const Knights&>(s);
if (!scene)
initialize();
QList <QGraphicsItem*> itemList = scene->items();
foreach (QGraphicsItem* i, scene->items()) {
scene->removeItem(i);
delete i;
}
for (int i=0; i<k.n; i++) {
for (int j=0; j<k.n; j++) {
scene->addRect(i*unit,j*unit,unit,unit);
QPen pen(Qt::black, 2);
if (!k.succ[i*k.n+j].assigned()) {
pen.setColor(Qt::red);
pen.setStyle(Qt::DotLine);
pen.setWidth(0);
}
for (IntVarValues xv(k.succ[i*k.n+j]); xv(); ++xv) {
int ky = xv.val() % k.n;
int kx = xv.val() / k.n;
scene->addLine(i*unit+unit/2,j*unit+unit/2,
kx*unit+unit/2,ky*unit+unit/2,
pen);
}
}
}
mw->show();
}
/// Set up main window
void initialize(void) {
mw = new QMainWindow();
scene = new QGraphicsScene();
QGraphicsView* view = new QGraphicsView(scene);
view->setRenderHints(QPainter::Antialiasing);
mw->setCentralWidget(view);
mw->setAttribute(Qt::WA_QuitOnClose, false);
mw->setAttribute(Qt::WA_DeleteOnClose, false);
QAction* closeWindow = new QAction("Close window", mw);
closeWindow->setShortcut(QKeySequence("Ctrl+W"));
mw->connect(closeWindow, SIGNAL(triggered()),
mw, SLOT(close()));
mw->addAction(closeWindow);
}
/// Name of the inspector
virtual std::string name(void) { return "Board"; }
/// Finalize inspector
virtual void finalize(void) {
delete mw;
mw = NULL;
}
};
#endif GECODE_HAS_GIST
/** \brief Main-function
* \relates Knights
*/
int
main(int argc, char* argv[]) {
SizeOptions opt("Knights");
opt.iterations(100);
opt.size(8);
opt.propagation(Knights::PROP_CIRCUIT);
opt.propagation(Knights::PROP_REIFIED, "reified");
opt.propagation(Knights::PROP_CIRCUIT, "circuit");
opt.branching(Knights::BRANCH_NAIVE);
opt.branching(Knights::BRANCH_NAIVE, "reified");
opt.branching(Knights::BRANCH_WARNSDORFF, "warnsdorff");
#ifdef GECODE_HAS_GIST
KnightsInspector ki;
opt.inspect.click(&ki);
#endif
opt.parse(argc,argv);
if (opt.propagation() == Knights::PROP_REIFIED) {
Script::run<KnightsReified,DFS,SizeOptions>(opt);
} else {
Script::run<KnightsCircuit,DFS,SizeOptions>(opt);
}
return 0;
}
// STATISTICS: example-any
|