132 lines
4.0 KiB
C#
132 lines
4.0 KiB
C#
// Copyright 2010-2022 Google LLC
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// [START program]
|
|
// [START import]
|
|
using System;
|
|
using Google.OrTools.ModelBuilder;
|
|
// [END import]
|
|
|
|
// [START program_part1]
|
|
public class BinPackingMb
|
|
{
|
|
// [START data_model]
|
|
class DataModel
|
|
{
|
|
public static double[] Weights = { 48, 30, 19, 36, 36, 27, 42, 42, 36, 24, 30 };
|
|
public int NumItems = Weights.Length;
|
|
public int NumBins = Weights.Length;
|
|
public double BinCapacity = 100.0;
|
|
}
|
|
// [END data_model]
|
|
public static void Main()
|
|
{
|
|
// [START data]
|
|
DataModel data = new DataModel();
|
|
// [END data]
|
|
// [END program_part1]
|
|
|
|
// [START model]
|
|
Model model = new Model();
|
|
// [END model]
|
|
|
|
// [START program_part2]
|
|
// [START variables]
|
|
Variable[,] x = new Variable[data.NumItems, data.NumBins];
|
|
for (int i = 0; i < data.NumItems; i++)
|
|
{
|
|
for (int j = 0; j < data.NumBins; j++)
|
|
{
|
|
x[i, j] = model.NewBoolVar($"x_{i}_{j}");
|
|
}
|
|
}
|
|
Variable[] y = new Variable[data.NumBins];
|
|
for (int j = 0; j < data.NumBins; j++)
|
|
{
|
|
y[j] = model.NewBoolVar($"y_{j}");
|
|
}
|
|
// [END variables]
|
|
|
|
// [START constraints]
|
|
for (int i = 0; i < data.NumItems; ++i)
|
|
{
|
|
var assignedWork = LinearExpr.NewBuilder();
|
|
for (int j = 0; j < data.NumBins; ++j)
|
|
{
|
|
assignedWork.Add(x[i, j]);
|
|
}
|
|
model.Add(assignedWork == 1);
|
|
}
|
|
|
|
for (int j = 0; j < data.NumBins; ++j)
|
|
{
|
|
var load = LinearExpr.NewBuilder();
|
|
for (int i = 0; i < data.NumItems; ++i)
|
|
{
|
|
load.AddTerm(x[i, j], DataModel.Weights[i]);
|
|
}
|
|
model.Add(y[j] * data.BinCapacity >= load);
|
|
}
|
|
// [END constraints]
|
|
|
|
// [START objective]
|
|
model.Minimize(LinearExpr.Sum(y));
|
|
// [END objective]
|
|
|
|
// [START solver]
|
|
// Create the solver with the SCIP backend and check it is supported.
|
|
Solver solver = new Solver("SCIP");
|
|
if (!solver.SolverIsSupported())
|
|
{
|
|
return;
|
|
}
|
|
// [END solver]
|
|
|
|
// [START solve]
|
|
SolveStatus resultStatus = solver.Solve(model);
|
|
// [END solve]
|
|
|
|
// [START print_solution]
|
|
// Check that the problem has an optimal solution.
|
|
if (resultStatus != SolveStatus.OPTIMAL)
|
|
{
|
|
Console.WriteLine("The problem does not have an optimal solution!");
|
|
return;
|
|
}
|
|
Console.WriteLine($"Number of bins used: {solver.ObjectiveValue}");
|
|
double TotalWeight = 0.0;
|
|
for (int j = 0; j < data.NumBins; ++j)
|
|
{
|
|
double BinWeight = 0.0;
|
|
if (solver.Value(y[j]) == 1)
|
|
{
|
|
Console.WriteLine($"Bin {j}");
|
|
for (int i = 0; i < data.NumItems; ++i)
|
|
{
|
|
if (solver.Value(x[i, j]) == 1)
|
|
{
|
|
Console.WriteLine($"Item {i} weight: {DataModel.Weights[i]}");
|
|
BinWeight += DataModel.Weights[i];
|
|
}
|
|
}
|
|
Console.WriteLine($"Packed bin weight: {BinWeight}");
|
|
TotalWeight += BinWeight;
|
|
}
|
|
}
|
|
Console.WriteLine($"Total packed weight: {TotalWeight}");
|
|
// [END print_solution]
|
|
}
|
|
}
|
|
// [END program_part2]
|
|
// [END program]
|