405 lines
12 KiB
C#
405 lines
12 KiB
C#
// Copyright 2010-2017 Google
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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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using System;
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using Google.OrTools.Sat;
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public class VarArraySolutionPrinter : CpSolverSolutionCallback
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{
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public VarArraySolutionPrinter(IntVar[] variables)
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{
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variables_ = variables;
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}
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public override void OnSolutionCallback()
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{
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{
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Console.WriteLine(String.Format("Solution #{0}: time = {1:F2} s",
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solution_count_, WallTime()));
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foreach (IntVar v in variables_)
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{
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Console.WriteLine(
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String.Format(" {0} = {1}", v.ShortString(), Value(v)));
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}
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solution_count_++;
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}
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}
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public int SolutionCount()
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{
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return solution_count_;
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}
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private int solution_count_;
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private IntVar[] variables_;
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}
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public class VarArraySolutionPrinterWithObjective : CpSolverSolutionCallback
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{
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public VarArraySolutionPrinterWithObjective(IntVar[] variables)
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{
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variables_ = variables;
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}
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public override void OnSolutionCallback()
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{
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{
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Console.WriteLine(String.Format("Solution #{0}: time = {1:F2} s",
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solution_count_, WallTime()));
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Console.WriteLine(
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String.Format(" objective value = {0}", ObjectiveValue()));
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foreach (IntVar v in variables_)
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{
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Console.WriteLine(
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String.Format(" {0} = {1}", v.ShortString(), Value(v)));
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}
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solution_count_++;
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}
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}
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public int SolutionCount()
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{
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return solution_count_;
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}
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private int solution_count_;
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private IntVar[] variables_;
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}
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public class CodeSamplesSat
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{
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static void CodeSample()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the Boolean variable.
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IntVar x = model.NewBoolVar("x");
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}
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static void LiteralSample()
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{
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CpModel model = new CpModel();
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IntVar x = model.NewBoolVar("x");
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ILiteral not_x = x.Not();
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}
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static void BoolOrSample()
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{
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CpModel model = new CpModel();
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IntVar x = model.NewBoolVar("x");
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IntVar y = model.NewBoolVar("y");
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model.AddBoolOr(new ILiteral[] {x, y.Not()});
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}
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static void ReifiedSample()
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{
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CpModel model = new CpModel();
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IntVar x = model.NewBoolVar("x");
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IntVar y = model.NewBoolVar("y");
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IntVar b = model.NewBoolVar("b");
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// First version using a half-reified bool and.
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model.AddBoolAnd(new ILiteral[] {x, y.Not()}).OnlyEnforceIf(b);
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// Second version using implications.
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model.AddImplication(b, x);
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model.AddImplication(b, y.Not());
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// Third version using bool or.
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model.AddBoolOr(new ILiteral[] {b.Not(), x});
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model.AddBoolOr(new ILiteral[] {b.Not(), y.Not()});
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}
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static void RabbitsAndPheasants()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the variables.
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IntVar r = model.NewIntVar(0, 100, "r");
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IntVar p = model.NewIntVar(0, 100, "p");
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// 20 heads.
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model.Add(r + p == 20);
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// 56 legs.
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model.Add(4 * r + 2 * p == 56);
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// Creates a solver and solves the model.
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CpSolver solver = new CpSolver();
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CpSolverStatus status = solver.Solve(model);
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if (status == CpSolverStatus.Feasible)
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{
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Console.WriteLine(solver.Value(r) + " rabbits, and " +
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solver.Value(p) + " pheasants");
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}
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}
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static void BinpackingProblem()
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{
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// Data.
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int bin_capacity = 100;
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int slack_capacity = 20;
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int num_bins = 10;
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int[,] items = new int[,] { {20, 12}, {15, 12}, {30, 8}, {45, 5} };
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int num_items = items.GetLength(0);
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// Model.
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CpModel model = new CpModel();
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// Main variables.
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IntVar[,] x = new IntVar[num_items, num_bins];
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for (int i = 0; i < num_items; ++i)
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{
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int num_copies = items[i, 1];
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for (int b = 0; b < num_bins; ++b)
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{
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x[i, b] = model.NewIntVar(0, num_copies, String.Format("x_{0}_{1}", i, b));
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}
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}
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// Load variables.
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IntVar[] load = new IntVar[num_bins];
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for (int b = 0; b < num_bins; ++b)
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{
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load[b] = model.NewIntVar(0, bin_capacity, String.Format("load_{0}", b));
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}
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// Slack variables.
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IntVar[] slacks = new IntVar[num_bins];
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for (int b = 0; b < num_bins; ++b)
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{
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slacks[b] = model.NewBoolVar(String.Format("slack_{0}", b));
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}
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// Links load and x.
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int[] sizes = new int[num_items];
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for (int i = 0; i < num_items; ++i) {
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sizes[i] = items[i, 0];
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}
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for (int b = 0; b < num_bins; ++b)
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{
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IntVar[] tmp = new IntVar[num_items];
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for (int i = 0; i < num_items; ++i)
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{
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tmp[i] = x[i, b];
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}
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model.Add(load[b] == tmp.ScalProd(sizes));
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}
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// Place all items.
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for (int i = 0; i < num_items; ++i)
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{
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IntVar[] tmp = new IntVar[num_bins];
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for (int b = 0; b < num_bins; ++b)
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{
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tmp[b] = x[i, b];
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}
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model.Add(tmp.Sum() == items[i, 1]);
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}
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// Links load and slack.
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int safe_capacity = bin_capacity - slack_capacity;
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for (int b = 0; b < num_bins; ++b)
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{
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// slack[b] => load[b] <= safe_capacity.
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model.Add(load[b] <= safe_capacity).OnlyEnforceIf(slacks[b]);
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// not(slack[b]) => load[b] > safe_capacity.
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model.Add(load[b] > safe_capacity).OnlyEnforceIf(slacks[b].Not());
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}
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// Maximize sum of slacks.
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model.Maximize(slacks.Sum());
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// Solves and prints out the solution.
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CpSolver solver = new CpSolver();
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CpSolverStatus status = solver.Solve(model);
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Console.WriteLine(String.Format("Solve status: {0}", status));
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if (status == CpSolverStatus.Optimal) {
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Console.WriteLine(String.Format("Optimal objective value: {0}",
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solver.ObjectiveValue));
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for (int b = 0; b < num_bins; ++b)
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{
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Console.WriteLine(String.Format("load_{0} = {1}",
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b, solver.Value(load[b])));
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for (int i = 0; i < num_items; ++i)
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{
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Console.WriteLine(string.Format(" item_{0}_{1} = {2}",
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i, b, solver.Value(x[i, b])));
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}
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}
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}
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Console.WriteLine("Statistics");
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Console.WriteLine(
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String.Format(" - conflicts : {0}", solver.NumConflicts()));
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Console.WriteLine(
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String.Format(" - branches : {0}", solver.NumBranches()));
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Console.WriteLine(
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String.Format(" - wall time : {0} s", solver.WallTime()));
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}
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static void IntervalSample()
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{
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CpModel model = new CpModel();
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int horizon = 100;
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IntVar start_var = model.NewIntVar(0, horizon, "start");
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// C# code supports IntVar or integer constants in intervals.
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int duration = 10;
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IntVar end_var = model.NewIntVar(0, horizon, "end");
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IntervalVar interval =
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model.NewIntervalVar(start_var, duration, end_var, "interval");
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}
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static void OptionalIntervalSample()
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{
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CpModel model = new CpModel();
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int horizon = 100;
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IntVar start_var = model.NewIntVar(0, horizon, "start");
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// C# code supports IntVar or integer constants in intervals.
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int duration = 10;
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IntVar end_var = model.NewIntVar(0, horizon, "end");
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IntVar presence_var = model.NewBoolVar("presence");
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IntervalVar interval = model.NewOptionalIntervalVar(
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start_var, duration, end_var, presence_var, "interval");
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}
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static void MinimalCpSat()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the variables.
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int num_vals = 3;
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IntVar x = model.NewIntVar(0, num_vals - 1, "x");
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IntVar y = model.NewIntVar(0, num_vals - 1, "y");
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IntVar z = model.NewIntVar(0, num_vals - 1, "z");
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// Creates the constraints.
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model.Add(x != y);
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// Creates a solver and solves the model.
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CpSolver solver = new CpSolver();
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CpSolverStatus status = solver.Solve(model);
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if (status == CpSolverStatus.Feasible)
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{
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Console.WriteLine("x = " + solver.Value(x));
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Console.WriteLine("y = " + solver.Value(y));
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Console.WriteLine("z = " + solver.Value(z));
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}
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}
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static void MinimalCpSatWithTimeLimit()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the variables.
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int num_vals = 3;
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IntVar x = model.NewIntVar(0, num_vals - 1, "x");
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IntVar y = model.NewIntVar(0, num_vals - 1, "y");
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IntVar z = model.NewIntVar(0, num_vals - 1, "z");
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// Creates the constraints.
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model.Add(x != y);
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// Creates a solver and solves the model.
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CpSolver solver = new CpSolver();
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// Adds a time limit. Parameters are stored as strings in the solver.
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solver.StringParameters = "max_time_in_seconds:10.0" ;
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CpSolverStatus status = solver.Solve(model);
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if (status == CpSolverStatus.Feasible)
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{
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Console.WriteLine("x = " + solver.Value(x));
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Console.WriteLine("y = " + solver.Value(y));
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Console.WriteLine("z = " + solver.Value(z));
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}
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}
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static void MinimalCpSatPrintIntermediateSolutions()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the variables.
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int num_vals = 3;
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IntVar x = model.NewIntVar(0, num_vals - 1, "x");
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IntVar y = model.NewIntVar(0, num_vals - 1, "y");
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IntVar z = model.NewIntVar(0, num_vals - 1, "z");
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// Creates the constraints.
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model.Add(x != y);
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// Create the objective.
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model.Maximize(x + 2 * y + 3 * z);
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// Creates a solver and solves the model.
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CpSolver solver = new CpSolver();
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VarArraySolutionPrinterWithObjective cb =
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new VarArraySolutionPrinterWithObjective(new IntVar[] {x, y, z});
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solver.SearchAllSolutions(model, cb);
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Console.WriteLine(String.Format("Number of solutions found: {0}",
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cb.SolutionCount()));
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}
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static void MinimalCpSatAllSolutions()
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{
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// Creates the model.
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CpModel model = new CpModel();
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// Creates the variables.
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int num_vals = 3;
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IntVar x = model.NewIntVar(0, num_vals - 1, "x");
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IntVar y = model.NewIntVar(0, num_vals - 1, "y");
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IntVar z = model.NewIntVar(0, num_vals - 1, "z");
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// Creates the constraints.
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model.Add(x != y);
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// Creates a solver and solves the model.
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CpSolver solver = new CpSolver();
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VarArraySolutionPrinter cb =
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new VarArraySolutionPrinter(new IntVar[] {x, y, z});
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solver.SearchAllSolutions(model, cb);
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Console.WriteLine(String.Format("Number of solutions found: {0}",
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cb.SolutionCount()));
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}
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static void Main()
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{
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Console.WriteLine("--- CodeSample ---");
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CodeSample();
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Console.WriteLine("--- LiteralSample ---");
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LiteralSample();
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Console.WriteLine("--- BoolOrSample ---");
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BoolOrSample();
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Console.WriteLine("--- ReifiedSample ---");
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ReifiedSample();
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Console.WriteLine("--- RabbitsAndPheasants ---");
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RabbitsAndPheasants();
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Console.WriteLine("--- BinpackingProblem ---");
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BinpackingProblem();
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Console.WriteLine("--- IntervalSample ---");
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IntervalSample();
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Console.WriteLine("--- OptionalIntervalSample ---");
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OptionalIntervalSample();
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Console.WriteLine("--- MinimalCpSat ---");
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MinimalCpSat();
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Console.WriteLine("--- MinimalCpSatWithTimeLimit ---");
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MinimalCpSatWithTimeLimit();
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Console.WriteLine("--- MinimalCpSatPrintIntermediateSolutions ---");
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MinimalCpSatPrintIntermediateSolutions();
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Console.WriteLine("--- MinimalCpSatAllSolutions ---");
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MinimalCpSatAllSolutions();
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}
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}
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