ortools-clone/examples/cpp/linear_assignment_api.cc

// Copyright 2010-2012 Google
// 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.

#include "base/commandlineflags.h"
#include "base/logging.h"
#include "graph/ebert_graph.h"
#include "graph/linear_assignment.h"

namespace operations_research {

// Test assignment on a 4x4 matrix. Example taken from
// http://www.ee.oulu.fi/~mpa/matreng/eem1_2-1.htm with kCost[0][1]
// modified so the optimum solution is unique.
void AssignmentOn4x4Matrix() {
  LOG(INFO) << "Assignment on 4x4 Matrix";
  const int kNumSources = 4;
  const int kNumTargets = 4;
  const CostValue kCost[kNumSources][kNumTargets] = {
    { 90, 76, 75, 80 },
    { 35, 85, 55, 65 },
    { 125, 95, 90, 105 },
    { 45, 110, 95, 115 }
  };
  const CostValue kExpectedCost =
      kCost[0][3] + kCost[1][2] + kCost[2][1] + kCost[3][0];
  ForwardStarGraph graph(
      kNumSources + kNumTargets, kNumSources * kNumTargets);
  LinearSumAssignment<ForwardStarGraph> assignment(graph, kNumSources);
  for (NodeIndex source = 0; source < kNumSources; ++source) {
    for (NodeIndex target = 0; target < kNumTargets; ++target) {
      ArcIndex arc = graph.AddArc(source, kNumSources + target);
      assignment.SetArcCost(arc, kCost[source][target]);
    }
  }
  CHECK(assignment.ComputeAssignment());
  CostValue total_cost = assignment.GetCost();
  CHECK_EQ(kExpectedCost, total_cost);
}

}  // namespace operations_research

int main(int argc, char **argv) {
  google::ParseCommandLineFlags(&argc, &argv, true);
  operations_research::AssignmentOn4x4Matrix();
  return 0;
}