141 lines
3.4 KiB
C#
141 lines
3.4 KiB
C#
// Copyright 2010-2018 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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namespace Google.OrTools.LinearSolver
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{
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using System;
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using System.Collections.Generic;
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public class LinearConstraint
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{
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public virtual String ToString()
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{
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return "LinearConstraint";
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}
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public virtual Constraint Extract(Solver solver)
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{
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return null;
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}
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}
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public class RangeConstraint : LinearConstraint
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{
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public RangeConstraint(LinearExpr expr, double lb, double ub)
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{
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this.expr_ = expr;
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this.lb_ = lb;
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this.ub_ = ub;
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}
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public override String ToString()
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{
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return "" + lb_ + " <= " + expr_.ToString() + " <= " + ub_;
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}
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public override Constraint Extract(Solver solver)
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{
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Dictionary<Variable, double> coefficients =
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new Dictionary<Variable, double>();
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double constant = expr_.Visit(coefficients);
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Constraint ct = solver.MakeConstraint(lb_ - constant, ub_ - constant);
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foreach (KeyValuePair<Variable, double> pair in coefficients)
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{
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ct.SetCoefficient(pair.Key, pair.Value);
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}
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return ct;
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}
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public static implicit operator bool(RangeConstraint ct)
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{
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return false;
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}
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private LinearExpr expr_;
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private double lb_;
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private double ub_;
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}
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public class Equality : LinearConstraint
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{
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public Equality(LinearExpr left, LinearExpr right, bool equality)
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{
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this.left_ = left;
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this.right_ = right;
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this.equality_ = equality;
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}
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public override String ToString()
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{
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return "" + left_.ToString() + " == " + right_.ToString();
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}
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public override Constraint Extract(Solver solver)
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{
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Dictionary<Variable, double> coefficients =
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new Dictionary<Variable, double>();
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double constant = left_.Visit(coefficients);
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constant += right_.DoVisit(coefficients, -1);
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Constraint ct = solver.MakeConstraint(-constant, -constant);
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foreach (KeyValuePair<Variable, double> pair in coefficients)
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{
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ct.SetCoefficient(pair.Key, pair.Value);
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}
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return ct;
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}
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public static implicit operator bool(Equality ct)
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{
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return (object)ct.left_ == (object)ct.right_ ? ct.equality_ : !ct.equality_;
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}
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private LinearExpr left_;
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private LinearExpr right_;
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private bool equality_;
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}
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public class VarEquality : LinearConstraint
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{
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public VarEquality(Variable left, Variable right, bool equality)
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{
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this.left_ = left;
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this.right_ = right;
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this.equality_ = equality;
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}
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public override String ToString()
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{
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return "" + left_.Name() + " == " + right_.Name();
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}
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public override Constraint Extract(Solver solver)
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{
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Constraint ct = solver.MakeConstraint(0.0, 0.0);
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ct.SetCoefficient(left_, 1.0);
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ct.SetCoefficient(right_, -1.0);
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return ct;
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}
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public static implicit operator bool(VarEquality ct)
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{
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return (object)ct.left_ == (object)ct.right_ ? ct.equality_ : !ct.equality_;
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}
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private Variable left_;
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private Variable right_;
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private bool equality_;
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}
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} // namespace Google.OrTools.LinearSolver
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