SolverHelper.cs

// 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.

namespace Google.OrTools.LinearSolver
{
using System;
using System.Collections.Generic;

// Patch the MPSolver class to:
// - support custom versions of the array-based APIs (MakeVarArray, etc).
// - customize the construction, and the OptimizationProblemType enum.
// - support the natural language API.
public partial class Solver
{
    public Variable[] MakeVarArray(int count, double lb, double ub, bool integer)
    {
        Variable[] array = new Variable[count];
        for (int i = 0; i < count; ++i)
        {
            array[i] = MakeVar(lb, ub, integer, "");
        }
        return array;
    }

    public Variable[] MakeVarArray(int count, double lb, double ub, bool integer, string var_name)
    {
        Variable[] array = new Variable[count];
        for (int i = 0; i < count; ++i)
        {
            array[i] = MakeVar(lb, ub, integer, var_name + i);
        }
        return array;
    }

    public Variable[,] MakeVarMatrix(int rows, int cols, double lb, double ub, bool integer)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                matrix[i, j] = MakeVar(lb, ub, integer, "");
            }
        }
        return matrix;
    }

    public Variable[,] MakeVarMatrix(int rows, int cols, double lb, double ub, bool integer, string name)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                string var_name = name + "[" + i + ", " + j + "]";
                matrix[i, j] = MakeVar(lb, ub, integer, var_name);
            }
        }
        return matrix;
    }

    public Variable[] MakeNumVarArray(int count, double lb, double ub)
    {
        return MakeVarArray(count, lb, ub, false);
    }

    public Variable[] MakeNumVarArray(int count, double lb, double ub, string var_name)
    {
        return MakeVarArray(count, lb, ub, false, var_name);
    }

    public Variable[,] MakeNumVarMatrix(int rows, int cols, double lb, double ub)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                matrix[i, j] = MakeNumVar(lb, ub, "");
            }
        }
        return matrix;
    }

    public Variable[,] MakeNumVarMatrix(int rows, int cols, double lb, double ub, string name)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                string var_name = name + "[" + i + ", " + j + "]";
                matrix[i, j] = MakeNumVar(lb, ub, var_name);
            }
        }
        return matrix;
    }

    public Variable[] MakeIntVarArray(int count, double lb, double ub)
    {
        return MakeVarArray(count, lb, ub, true);
    }

    public Variable[] MakeIntVarArray(int count, double lb, double ub, string var_name)
    {
        return MakeVarArray(count, lb, ub, true, var_name);
    }

    public Variable[,] MakeIntVarMatrix(int rows, int cols, double lb, double ub)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                matrix[i, j] = MakeIntVar(lb, ub, "");
            }
        }
        return matrix;
    }

    public Variable[,] MakeIntVarMatrix(int rows, int cols, double lb, double ub, string name)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                string var_name = name + "[" + i + ", " + j + "]";
                matrix[i, j] = MakeIntVar(lb, ub, var_name);
            }
        }
        return matrix;
    }

    public Variable[] MakeBoolVarArray(int count)
    {
        return MakeVarArray(count, 0.0, 1.0, true);
    }

    public Variable[] MakeBoolVarArray(int count, string var_name)
    {
        return MakeVarArray(count, 0.0, 1.0, true, var_name);
    }

    public Variable[,] MakeBoolVarMatrix(int rows, int cols)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                matrix[i, j] = MakeBoolVar("");
            }
        }
        return matrix;
    }

    public Variable[,] MakeBoolVarMatrix(int rows, int cols, string name)
    {
        Variable[,] matrix = new Variable[rows, cols];
        for (int i = 0; i < rows; ++i)
        {
            for (int j = 0; j < cols; ++j)
            {
                string var_name = name + "[" + i + ", " + j + "]";
                matrix[i, j] = MakeBoolVar(var_name);
            }
        }
        return matrix;
    }

    public Constraint Add(LinearConstraint constraint)
    {
        return constraint.Extract(this);
    }

    public void Minimize(LinearExpr expr)
    {
        Objective().Clear();
        Objective().SetMinimization();
        Dictionary<Variable, double> coefficients = new Dictionary<Variable, double>();
        double constant = expr.Visit(coefficients);
        foreach (KeyValuePair<Variable, double> pair in coefficients)
        {
            Objective().SetCoefficient(pair.Key, pair.Value);
        }
        Objective().SetOffset(constant);
    }

    public void Maximize(LinearExpr expr)
    {
        Objective().Clear();
        Objective().SetMaximization();
        Dictionary<Variable, double> coefficients = new Dictionary<Variable, double>();
        double constant = expr.Visit(coefficients);
        foreach (KeyValuePair<Variable, double> pair in coefficients)
        {
            Objective().SetCoefficient(pair.Key, pair.Value);
        }
        Objective().SetOffset(constant);
    }

    public void Minimize(Variable var)
    {
        Objective().Clear();
        Objective().SetMinimization();
        Objective().SetCoefficient(var, 1.0);
    }

    public void Maximize(Variable var)
    {
        Objective().Clear();
        Objective().SetMaximization();
        Objective().SetCoefficient(var, 1.0);
    }
}

} // namespace Google.OrTools.LinearSolver