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bnd.hpp

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00001 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
00002 /*
00003  *  Main authors:
00004  *     Christian Schulte <schulte@gecode.org>
00005  *
00006  *  Copyright:
00007  *     Christian Schulte, 2003
00008  *
00009  *  This file is part of Gecode, the generic constraint
00010  *  development environment:
00011  *     http://www.gecode.org
00012  *
00013  *  Permission is hereby granted, free of charge, to any person obtaining
00014  *  a copy of this software and associated documentation files (the
00015  *  "Software"), to deal in the Software without restriction, including
00016  *  without limitation the rights to use, copy, modify, merge, publish,
00017  *  distribute, sublicense, and/or sell copies of the Software, and to
00018  *  permit persons to whom the Software is furnished to do so, subject to
00019  *  the following conditions:
00020  *
00021  *  The above copyright notice and this permission notice shall be
00022  *  included in all copies or substantial portions of the Software.
00023  *
00024  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00025  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00026  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00027  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00028  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00029  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00030  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00031  *
00032  */
00033 
00034 namespace Gecode { namespace Int { namespace Distinct {
00035 
00036   template<class View>
00037   forceinline
00038   Bnd<View>::Bnd(Home home, ViewArray<View>& x0)
00039     : Propagator(home), x(x0), y(home,x0) {
00040     // Both x and y initially contain the same variables
00041     //  - x is used for bounds propagation
00042     //  - y is used for performing singleton propagation
00043     // They can not be shared as singleton propagation removes
00044     // determined variables still required for bounds propagation.
00045     y.subscribe(home,*this,PC_INT_BND);
00046     int min = x[0].min(), max = x[0].max();
00047     for (int i=1; i<x.size(); i++) {
00048       min = std::min(min,x[i].min());
00049       max = std::max(max,x[i].max());
00050     }
00051     min_x = min; max_x = max;
00052   }
00053 
00054   template<class View>
00055   forceinline size_t
00056   Bnd<View>::dispose(Space& home) {
00057     y.cancel(home,*this,PC_INT_BND);
00058     (void) Propagator::dispose(home);
00059     return sizeof(*this);
00060   }
00061 
00062   template<class View>
00063   forceinline
00064   Bnd<View>::Bnd(Space& home, Bnd<View>& p)
00065     : Propagator(home,p), min_x(p.min_x), max_x(p.max_x) {
00066     x.update(home,p.x);
00067     y.update(home,p.y);
00068   }
00069 
00070   template<class View>
00071   Actor*
00072   Bnd<View>::copy(Space& home) {
00073     return new (home) Bnd<View>(home,*this);
00074   }
00075 
00076   template<class View>
00077   PropCost
00078   Bnd<View>::cost(const Space&, const ModEventDelta& med) const {
00079     if (View::me(med) == ME_INT_VAL)
00080       return PropCost::linear(PropCost::LO, y.size());
00081     else
00082       return PropCost::quadratic(PropCost::LO, x.size());
00083   }
00084 
00085   template<class View>
00086   void
00087   Bnd<View>::reschedule(Space& home) {
00088     y.reschedule(home,*this,PC_INT_BND);
00089   }
00090 
00091 
00093   class Rank {
00094   public:
00095     int min, max;
00096   };
00097 
00099   template<class View>
00100   class MaxIncIdx {
00101   protected:
00102     ViewArray<View> x;
00103   public:
00104     forceinline
00105     MaxIncIdx(const ViewArray<View>& x0) : x(x0) {}
00106     forceinline bool
00107     operator ()(const int i, const int j) {
00108       return x[i].max() < x[j].max();
00109     }
00110   };
00111 
00113   template<class View>
00114   class MinIncIdx {
00115   protected:
00116     ViewArray<View> x;
00117   public:
00118     forceinline
00119     MinIncIdx(const ViewArray<View>& x0) : x(x0) {}
00120     forceinline bool
00121     operator ()(const int i, const int j) {
00122       return x[i].min() < x[j].min();
00123     }
00124   };
00125 
00127   template<class View>
00128   class MinInc {
00129   public:
00130     forceinline bool
00131     operator ()(const View& x, const View& y) {
00132       return x.min() < y.min();
00133     }
00134   };
00135 
00137   template<class IntType>
00138   class HallInfo {
00139   public:
00140     IntType bounds, t, d, h;
00141   };
00142 
00143   template<class IntType>
00144   forceinline void
00145   pathset_t(HallInfo<IntType> hall[],
00146             IntType start, IntType end, IntType to) {
00147     IntType k, l;
00148     for (l=start; (k=l) != end; hall[k].t=to) {
00149       l = hall[k].t;
00150     }
00151   }
00152 
00153   template<class IntType>
00154   forceinline void
00155   pathset_h(HallInfo<IntType> hall[],
00156             IntType start, IntType end, IntType to) {
00157     IntType k, l;
00158     for (l=start; (k=l) != end; hall[k].h=to) {
00159       l = hall[k].h;
00160     }
00161   }
00162 
00163   template<class IntType>
00164   forceinline IntType
00165   pathmin_h(const HallInfo<IntType> hall[], IntType i) {
00166     while (hall[i].h < i)
00167       i = hall[i].h;
00168     return i;
00169   }
00170 
00171   template<class IntType>
00172   forceinline IntType
00173   pathmin_t(const HallInfo<IntType> hall[], IntType i) {
00174     while (hall[i].t < i)
00175       i = hall[i].t;
00176     return i;
00177   }
00178 
00179   template<class IntType>
00180   forceinline IntType
00181   pathmax_h(const HallInfo<IntType> hall[], IntType i) {
00182     while (hall[i].h > i)
00183       i = hall[i].h;
00184     return i;
00185   }
00186 
00187   template<class IntType>
00188   forceinline IntType
00189   pathmax_t(const HallInfo<IntType> hall[], IntType i) {
00190     while (hall[i].t > i)
00191       i = hall[i].t;
00192     return i;
00193   }
00194 
00195   template<class View, class IntType>
00196   forceinline ExecStatus
00197   prop_bnd(Space& home, ViewArray<View>& x,
00198            int* minsorted, int* maxsorted) {
00199     const int n = x.size();
00200 
00201     Region r;
00202 
00203     // Setup rank and bounds info
00204     HallInfo<IntType>* hall = r.alloc<HallInfo<IntType> >(2*n+2);
00205     Rank* rank = r.alloc<Rank>(n);
00206 
00207     int nb = 0;
00208     {
00209       IntType min  = x[minsorted[0]].min();
00210       IntType max  = x[maxsorted[0]].max() + 1;
00211       IntType last = min - 2;
00212 
00213       hall[0].bounds = last;
00214 
00215       int i = 0;
00216       int j = 0;
00217       while (true) {
00218         if ((i < n) && (min < max)) {
00219           if (min != last)
00220             hall[++nb].bounds = last = min;
00221           rank[minsorted[i]].min = nb;
00222           if (++i < n)
00223             min = x[minsorted[i]].min();
00224         } else {
00225           if (max != last)
00226             hall[++nb].bounds = last = max;
00227           rank[maxsorted[j]].max = nb;
00228           if (++j == n)
00229             break;
00230           max = x[maxsorted[j]].max() + 1;
00231         }
00232       }
00233       hall[nb+1].bounds = hall[nb].bounds + 2;
00234     }
00235 
00236     // If tells cross holes, we do not compute a fixpoint
00237     ExecStatus es = ES_FIX;
00238 
00239     // Propagate lower bounds
00240     for (int i=nb+2; --i;) {
00241       hall[i].t = hall[i].h = i-1;
00242       hall[i].d = hall[i].bounds - hall[i-1].bounds;
00243     }
00244     for (int i=0; i<n; i++) { // visit intervals in increasing max order
00245       IntType x0 = rank[maxsorted[i]].min;
00246       IntType z = pathmax_t(hall, x0+1);
00247       IntType j = hall[z].t;
00248       if (--hall[z].d == 0)
00249         hall[z = pathmax_t(hall, hall[z].t=z+1)].t = j;
00250       pathset_t(hall, x0+1, z, z); // path compression
00251       IntType y = rank[maxsorted[i]].max;
00252       if (hall[z].d < hall[z].bounds-hall[y].bounds)
00253         return ES_FAILED;
00254       if (hall[x0].h > x0) {
00255         IntType w = pathmax_h(hall, hall[x0].h);
00256         IntType m = hall[w].bounds;
00257         ModEvent me = x[maxsorted[i]].gq(home,m);
00258         if (me_failed(me))
00259           return ES_FAILED;
00260         if ((me == ME_INT_VAL) ||
00261             ((me == ME_INT_BND) && (m != x[maxsorted[i]].min())))
00262           es = ES_NOFIX;
00263         pathset_h(hall, x0, w, w); // path compression
00264       }
00265       if (hall[z].d == hall[z].bounds-hall[y].bounds) {
00266         pathset_h(hall, hall[y].h, j-1, y); // mark hall interval
00267         hall[y].h = j-1;
00268       }
00269     }
00270 
00271     // Propagate upper bounds
00272     for (int i=nb+1; i--;) {
00273       hall[i].t = hall[i].h = i+1;
00274       hall[i].d = hall[i+1].bounds - hall[i].bounds;
00275     }
00276     for (int i=n; --i>=0; ) { // visit intervals in decreasing min order
00277       IntType x0 = rank[minsorted[i]].max;
00278       IntType z = pathmin_t(hall, x0-1);
00279       IntType j = hall[z].t;
00280       if (--hall[z].d == 0)
00281         hall[z = pathmin_t(hall, hall[z].t=z-1)].t = j;
00282       pathset_t(hall, x0-1, z, z);
00283       IntType y = rank[minsorted[i]].min;
00284       if (hall[z].d < hall[y].bounds-hall[z].bounds)
00285         return ES_FAILED;
00286       if (hall[x0].h < x0) {
00287         IntType w = pathmin_h(hall, hall[x0].h);
00288         IntType m = hall[w].bounds - 1;
00289         ModEvent me = x[minsorted[i]].lq(home,m);
00290         if (me_failed(me))
00291           return ES_FAILED;
00292         if ((me == ME_INT_VAL) ||
00293             ((me == ME_INT_BND) && (m != x[maxsorted[i]].min())))
00294           es = ES_NOFIX;
00295         pathset_h(hall, x0, w, w);
00296       }
00297       if (hall[z].d == hall[y].bounds-hall[z].bounds) {
00298         pathset_h(hall, hall[y].h, j+1, y);
00299         hall[y].h = j+1;
00300       }
00301     }
00302 
00303     return es;
00304   }
00305 
00306   template<class View>
00307   forceinline ExecStatus
00308   prop_bnd(Space& home, ViewArray<View>& x, int& min_x, int& max_x) {
00309 
00310     const int n = x.size();
00311 
00312     Region r;
00313 
00314     int* minsorted = r.alloc<int>(n);
00315     int* maxsorted = r.alloc<int>(n);
00316 
00317     unsigned int d = static_cast<unsigned int>(max_x - min_x) + 1;
00318 
00319     if (d < static_cast<unsigned int>(n))
00320       return ES_FAILED;
00321 
00322     if (d > 2*static_cast<unsigned int>(n)) {
00323       for (int i=0; i<n; i++)
00324         minsorted[i]=maxsorted[i]=i;
00325 
00326       MinIncIdx<View> min_inc(x);
00327       Support::quicksort<int,MinIncIdx<View> >(minsorted, n, min_inc);
00328       MaxIncIdx<View> max_inc(x);
00329       Support::quicksort<int,MaxIncIdx<View> >(maxsorted, n, max_inc);
00330     } else {
00331 
00332       int* minbucket = r.alloc<int>(d);
00333       int* maxbucket = r.alloc<int>(d);
00334       for (unsigned int i=0; i<d; i++)
00335         minbucket[i]=maxbucket[i]=0;
00336 
00337       for (int i=0; i<n; i++) {
00338         minbucket[x[i].min() - min_x]++;
00339         maxbucket[x[i].max() - min_x]++;
00340       }
00341 
00342       int c_min = 0, c_max = 0;
00343       for (unsigned int i=0; i<d; i++) {
00344         int t_min = minbucket[i];
00345         int t_max = maxbucket[i];
00346         minbucket[i] = c_min; c_min += t_min;
00347         maxbucket[i] = c_max; c_max += t_max;
00348       }
00349       assert((c_min == n) && (c_max == n));
00350 
00351       for (int i=n; i--; ) {
00352         minsorted[minbucket[x[i].min() - min_x]++] = i;
00353         maxsorted[maxbucket[x[i].max() - min_x]++] = i;
00354       }
00355     }
00356 
00357     // Update minimum and maximum information
00358     min_x = x[minsorted[0]].min();
00359     max_x = x[maxsorted[n-1]].max();
00360 
00361 
00362     if (d > (static_cast<unsigned int>(Int::Limits::max) / 2U))
00363       return prop_bnd<View,long long int>(home,x,minsorted,maxsorted);
00364     else
00365       return prop_bnd<View,int>(home,x,minsorted,maxsorted);
00366   }
00367 
00368   template<class View>
00369   ExecStatus
00370   prop_bnd(Space& home, ViewArray<View>& x) {
00371     int min = x[0].min(), max = x[0].max();
00372     for (int i=1; i<x.size(); i++) {
00373       min = std::min(min,x[i].min());
00374       max = std::max(max,x[i].max());
00375     }
00376     return prop_bnd(home, x, min, max);
00377   }
00378 
00379   template<class View>
00380   ExecStatus
00381   Bnd<View>::propagate(Space& home, const ModEventDelta& med) {
00382     assert(x.size() > 1);
00383 
00384     if (View::me(med) == ME_INT_VAL) {
00385       ExecStatus es = prop_val<View,false>(home,y);
00386       GECODE_ES_CHECK(es);
00387       if (y.size() < 2)
00388         return home.ES_SUBSUMED(*this);
00389       if (es == ES_FIX)
00390         return home.ES_FIX_PARTIAL(*this,View::med(ME_INT_BND));
00391     }
00392 
00393     if (y.size() == 2)
00394       GECODE_REWRITE(*this,(Rel::Nq<View,View>::post(home(*this),y[0],y[1])));
00395 
00396     ExecStatus es = prop_bnd<View>(home,x,min_x,max_x);
00397 
00398     GECODE_ES_CHECK(es);
00399     if (es == ES_NOFIX && View::me(modeventdelta()) ==  ME_INT_VAL)
00400       return es;
00401 
00402     const int n = x.size();
00403 
00404     if ((n > 2*y.size()) && (n > 6)) {
00405       // If there are many assigned views, try to eliminate them
00406       unsigned int d = static_cast<unsigned int>(max_x - min_x) + 1;
00407       if (d > 2*static_cast<unsigned int>(n)) {
00408         MinInc<View> min_inc;
00409         Support::quicksort<View,MinInc<View> >(&x[0], n, min_inc);
00410       } else {
00411         Region r;
00412         int* minbucket = r.alloc<int>(d);
00413         View* minsorted = r.alloc<View>(n);
00414 
00415         for (unsigned int i=0; i<d; i++)
00416           minbucket[i]=0;
00417         for (int i=0; i<n; i++)
00418           minbucket[x[i].min() - min_x]++;
00419 
00420         int c_min = 0;
00421         for (unsigned int i=0; i<d; i++) {
00422           int t_min = minbucket[i];
00423           minbucket[i] = c_min; c_min += t_min;
00424         }
00425         assert(c_min == n);
00426 
00427         for (int i=0; i<n; i++)
00428           minsorted[minbucket[x[i].min() - min_x]++] = x[i];
00429         for (int i=0; i<n; i++)
00430           x[i] = minsorted[i];
00431       }
00432 
00433       int i   = 0;
00434       int j   = 0;
00435       int max = x[0].max()-1;
00436       while (i < n-1) {
00437         if (!x[i].assigned() ||
00438             (x[i].val() <= max) || (x[i].val() > x[i+1].min())) {
00439           // Keep view x[i]
00440           max = std::max(max,x[i].max());
00441           x[j++]=x[i];
00442         }
00443         i++;
00444       }
00445       if (!x[i].assigned() || (x[i].val() <= max))
00446         x[j++]=x[i];
00447       x.size(j);
00448     }
00449 
00450     if (x.size() < 2)
00451       return home.ES_SUBSUMED(*this);
00452 
00453     if (x.size() == 2)
00454       GECODE_REWRITE(*this,(Rel::Nq<View,View>::post(home(*this),x[0],x[1])));
00455 
00456     return es;
00457   }
00458 
00459 #ifdef GECODE_HAS_CBS
00460   template<class View>
00461   void
00462   Bnd<View>::solndistrib(Space& home, Propagator::SendMarginal send) const {
00463     cbsdistinct(home,this->id(),x,send);
00464   }
00465 
00466   template<class View>
00467   void
00468   Bnd<View>::domainsizesum(Propagator::InDecision in, unsigned int& size,
00469                            unsigned int& size_b) const {
00470     cbssize(x,in,size,size_b);
00471   }
00472 #endif
00473 
00474   template<class View>
00475   ExecStatus
00476   Bnd<View>::post(Home home, ViewArray<View>& x){
00477     if (x.size() == 2)
00478       return Rel::Nq<View,View>::post(home,x[0],x[1]);
00479     if (x.size() > 2)
00480       (void) new (home) Bnd<View>(home,x);
00481     return ES_OK;
00482   }
00483 
00484 }}}
00485 
00486 // STATISTICS: int-prop
00487