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Linearize MakeScalProdEquality

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This commit is contained in:
lperron@google.com
2014-05-24 01:58:15 +00:00
parent 169dbd8aa3
commit e10756dedc
1 changed files with 48 additions and 2 deletions
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50
src/constraint_solver/expr_array.cc
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@@ -2253,7 +2253,7 @@ class ExprLinearizer : public ModelParser {
// ----- Factory functions -----
Constraint* MakeScalProdEqualityFct(Solver* const solver,
Constraint* MakeScalProdEqualityAux(Solver* const solver,
const std::vector<IntVar*>& vars,
const std::vector<int64>& coefficients,
int64 cst) {
@@ -2273,11 +2273,13 @@ Constraint* MakeScalProdEqualityFct(Solver* const solver,
if (AreAllOnes(coefficients)) {
return solver->MakeSumEquality(vars, cst);
}
if (AreAllBooleans(vars) && AreAllPositive(coefficients) && size > 2) {
if (AreAllBooleans(vars) &&
AreAllPositive(coefficients) && size > 2) {
// TODO(user) : bench BooleanScalProdEqVar with IntConst.
return solver->RevAlloc(
new PositiveBooleanScalProdEqCst(solver, vars, coefficients, cst));
}
// Simplications.
int constants = 0;
int positives = 0;
@@ -2381,6 +2383,50 @@ Constraint* MakeScalProdEqualityFct(Solver* const solver,
return solver->MakeSumEquality(terms, solver->MakeIntConst(cst));
}
Constraint* MakeScalProdEqualityFct(Solver* const solver,
const std::vector<IntVar*>& pre_vars,
const std::vector<int64>& pre_coefs,
int64 rhs) {
int64 constant = 0;
std::vector<IntVar*> vars;
std::vector<int64> coefs;
vars.reserve(pre_vars.size());
coefs.reserve(pre_coefs.size());
// Try linear scan of the variables to check if there is nothing to do.
bool ok = true;
for (int i = 0; i < pre_vars.size(); ++i) {
IntVar* const v = pre_vars[i];
const int64 c = pre_coefs[i];
if (v->Bound()) {
constant += c * v->Min();
} else if (solver->CastExpression(v) == nullptr) {
vars.push_back(v);
coefs.push_back(c);
} else {
ok = false;
vars.clear();
coefs.clear();
break;
}
}
if (!ok) {
// Instrospect the variables to simplify the sum.
hash_map<IntVar*, int64> map;
ExprLinearizer lin(&map);
for (int i = 0; i < pre_vars.size(); ++i) {
lin.Visit(pre_vars[i], pre_coefs[i]);
}
constant = lin.Constant();
for (const auto& iter : map) {
if (iter.second != 0) {
vars.push_back(iter.first);
coefs.push_back(iter.second);
}
}
}
return MakeScalProdEqualityAux(solver, vars, coefs, rhs - constant);
}
Constraint* MakeScalProdEqualityVarFct(Solver* const solver,
const std::vector<IntVar*>& vars,
const std::vector<int64>& coefficients,