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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- *//* * Main authors: * Christian Schulte <schulte@gecode.org> * * Copyright: * Christian Schulte, 2015 * * 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/int/rel.hh>
namespace Gecode { namespace Int { namespace Arithmetic {
template<class VA, class VB, bool tiebreak> forceinline ArgMax<VA,VB,tiebreak>::ArgMax(Home home, IdxViewArray<VA>& x0, VB y0) : Propagator(home), x(x0), y(y0) { x.subscribe(home,*this,PC_INT_BND); y.subscribe(home,*this,PC_INT_DOM); }
template<class VA, class VB, bool tiebreak> ExecStatus ArgMax<VA,VB,tiebreak>::post(Home home, IdxViewArray<VA>& x, VB y) { assert(x.size() > 0); if (x.size() == 1) { GECODE_ME_CHECK(y.eq(home,x[0].idx)); } else if (y.assigned()) { int max=0; while (x[max].idx < y.val()) max++; assert(x[max].idx == y.val()); if (tiebreak) for (int i=0; i<max; i++) GECODE_ES_CHECK((Rel::Le<VA,VA>::post(home, x[i].view,x[max].view))); else for (int i=0; i<max; i++) GECODE_ES_CHECK((Rel::Lq<VA,VA>::post(home, x[i].view,x[max].view))); for (int i=max+1; i<x.size(); i++) GECODE_ES_CHECK((Rel::Lq<VA,VA>::post(home, x[i].view,x[max].view))); } else { (void) new (home) ArgMax<VA,VB,tiebreak>(home,x,y); } return ES_OK; }
template<class VA, class VB, bool tiebreak> forceinline ArgMax<VA,VB,tiebreak>::ArgMax(Space& home, ArgMax<VA,VB,tiebreak>& p) : Propagator(home,p) { x.update(home,p.x); y.update(home,p.y); }
template<class VA, class VB, bool tiebreak> Actor* ArgMax<VA,VB,tiebreak>::copy(Space& home) { return new (home) ArgMax<VA,VB,tiebreak>(home,*this); }
template<class VA, class VB, bool tiebreak> PropCost ArgMax<VA,VB,tiebreak>::cost(const Space&, const ModEventDelta&) const { return PropCost::linear(PropCost::LO,x.size()+1); }
template<class VA, class VB, bool tiebreak> void ArgMax<VA,VB,tiebreak>::reschedule(Space& home) { x.reschedule(home,*this,PC_INT_BND); y.reschedule(home,*this,PC_INT_DOM); }
template<class VA, class VB, bool tiebreak> ExecStatus ArgMax<VA,VB,tiebreak>::propagate(Space& home, const ModEventDelta&) { /* * A key invariant is as follows: for each value i in the domain * of y there is an index-value pair with index i in x. */
// Compute lower and upper bounds for the maximum and its first position. int p = x[0].idx; int l = x[0].view.min(); int u = x[0].view.max(); for (int i=1; i<x.size(); i++) { if (l < x[i].view.min()) { p = x[i].idx; l = x[i].view.min(); } if (u < x[i].view.max()) u = x[i].view.max(); }
// Eliminate elements from x and y that are too small { Region r;
// Values to delete from y int* d=r.alloc<int>(y.size()); // Number of values to delete int n = 0;
int i=0, j=0; ViewValues<VB> iy(y);
while ((i < x.size()) && iy()) { if (x[i].idx == iy.val()) { if (x[i].view.max() < l) { x[i].view.cancel(home,*this,PC_INT_BND); d[n++]=x[i].idx; } else { x[j++]=x[i]; } ++iy; } else { assert(x[i].idx < iy.val()); if (x[i].view.max() < l) { x[i].view.cancel(home,*this,PC_INT_BND); } else { x[j++]=x[i]; } } i++; } while (i < x.size()) if (x[i].view.max() < l) { x[i].view.cancel(home,*this,PC_INT_BND); i++; } else { x[j++]=x[i++]; } x.size(j);
if (static_cast<unsigned int>(n) == y.size()) return ES_FAILED; Iter::Values::Array id(d,n); GECODE_ME_CHECK(y.minus_v(home,id,false)); }
/* * Now the following invariant holds: * - for all q in y: u >= x(q).max() >= l * - if l==u, then exists q in y: x(q).max = u */
if (tiebreak && (l == u)) GECODE_ME_CHECK(y.lq(home,p));
if (y.assigned()) { int max=0; while (x[max].idx < y.val()) max++; assert(x[max].idx == y.val()); if (tiebreak) for (int i=0; i<max; i++) GECODE_ES_CHECK((Rel::Le<VA,VA>::post(home(*this), x[i].view,x[max].view))); else for (int i=0; i<max; i++) GECODE_ES_CHECK((Rel::Lq<VA,VA>::post(home(*this), x[i].view,x[max].view))); for (int i=max+1; i<x.size(); i++) GECODE_ES_CHECK((Rel::Lq<VA,VA>::post(home(*this), x[i].view,x[max].view))); return home.ES_SUBSUMED(*this); }
// Recompute the upper bound for elements in y { ViewValues<VB> iy(y); int i=0; // Skip smaller elements while (x[i].idx < y.min()) i++; u=x[i].view.max(); // Skip the minimal element i++; ++iy; while (iy()) { if (x[i].idx == iy.val()) { u = std::max(u,x[i].view.max()); ++iy; } else { assert(x[i].idx < iy.val()); } i++; } }
// Constrain elements in x but not in y { int i = 0; // Elements which must be smaller (for tiebreaking) if (tiebreak) while ((i < x.size()) && (x[i].idx < y.min())) { GECODE_ME_CHECK(x[i].view.le(home,u)); i++; } else while ((i < x.size()) && (x[i].idx < y.min())) { GECODE_ME_CHECK(x[i].view.lq(home,u)); i++; } assert(x[i].idx == y.min());
// Elements which cannot be larger ViewValues<VB> iy(y); // Skip the minimal element i++; ++iy; while ((i < x.size()) && iy()) { if (x[i].idx == iy.val()) { ++iy; } else { assert(x[i].idx < iy.val()); GECODE_ME_CHECK(x[i].view.lq(home,u)); } i++; } while (i < x.size()) { assert(x[i].idx > y.max()); GECODE_ME_CHECK(x[i].view.lq(home,u)); i++; } } return tiebreak ? ES_NOFIX : ES_FIX; }
template<class VA, class VB, bool tiebreak> forceinline size_t ArgMax<VA,VB,tiebreak>::dispose(Space& home) { x.cancel(home,*this,PC_INT_BND); y.cancel(home,*this,PC_INT_DOM); (void) Propagator::dispose(home); return sizeof(*this); }
}}}
// STATISTICS: int-prop