combinatorial_auction2.cs

//
// Copyright 2012 Hakan Kjellerstrand
//
// 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.

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using Google.OrTools.ConstraintSolver;

public class CombinatorialAuction2
{
  /**
   *
   * Combinatorial auction.
   *
   * This is a more general model for the combinatorial example
   * in the Numberjack Tutorial, pages 9 and 24 (slides  19/175 and
   * 51/175).
   *
   * See http://www.hakank.org/or-tools/combinatorial_auction2.py
   *
   * The original and more talkative model is here:
   * http://www.hakank.org/numberjack/combinatorial_auction.py
   *
   */
  private static void Solve()
  {
    Solver solver = new Solver("CombinatorialAuction2");

    //
    // Data
    //
    int n = 5;

    // the items for each bid
    int[][] items = {
      new int[] {0,1},   // A,B
      new int[] {0,2},   // A, C
      new int[] {1,3},   // B,D
      new int[] {1,2,3}, // B,C,D
      new int[] {0}      // A
    };

    int[] bid_ids = {0,1,2,3};
    int[] bid_amount = {10,20,30,40,14};

    //
    // Decision variables
    //
    IntVar[] x = solver.MakeIntVarArray(n, 0, 1, "x");
    IntVar z = x.ScalProd(bid_amount).VarWithName("z");

    //
    // Constraints
    //

    foreach(int bid_id in bid_ids) {

      var tmp2 = (from item in Enumerable.Range(0, n)
                   from i in Enumerable.Range(0, items[item].Length)
                   where items[item][i] == bid_id
                   select x[item]);

      solver.Add(tmp2.ToArray().Sum() <= 1);

    }




    //
    // Objective
    //
    OptimizeVar obj = z.Maximize(1);

    //
    // Search
    //
    DecisionBuilder db = solver.MakePhase(x,
                                          Solver.CHOOSE_FIRST_UNBOUND,
                                          Solver.ASSIGN_MIN_VALUE);

    solver.NewSearch(db, obj);

    while (solver.NextSolution()) {
      Console.Write("z: {0,2} x: ", z.Value());
      for(int i = 0; i < n; i++) {
        Console.Write(x[i].Value() + " ");
      }
      Console.WriteLine();
    }

    Console.WriteLine("\nSolutions: {0}", solver.Solutions());
    Console.WriteLine("WallTime: {0}ms", solver.WallTime());
    Console.WriteLine("Failures: {0}", solver.Failures());
    Console.WriteLine("Branches: {0} ", solver.Branches());

    solver.EndSearch();

  }

  public static void Main(String[] args)
  {
    Solve();
  }
}