027f5cc3f8
C++: - [Up] linear_programming - [Up] integer_programming - constraint_programming_CP / rabbits_pheasants_cp - knapsack - max_flow / min_cost_flow - tsp / vrp note: previous "fuzzy" tsp has been renamed random_tsp. .Net: - vrp
68 lines
2.4 KiB
C++
68 lines
2.4 KiB
C++
// Copyright 2018 Google LLC
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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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// Knowing that we see 20 heads and 56 legs,
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// how many pheasants and rabbits are we looking at ?
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#include "ortools/base/logging.h"
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#include "ortools/constraint_solver/constraint_solver.h"
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namespace operations_research {
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void RunConstraintProgrammingExample() {
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// Instantiate the solver.
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Solver solver("RabbitsPheasantsExample");
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// Define decision variables.
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IntVar* const rabbits = solver.MakeIntVar(0, 20, "rabbits");
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IntVar* const pheasants = solver.MakeIntVar(0, 20, "pheasants");
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// Define constraints.
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IntExpr* const heads = solver.MakeSum(rabbits, pheasants);
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Constraint* const c0 = solver.MakeEquality(heads, 20);
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solver.AddConstraint(c0);
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IntExpr* const legs = solver.MakeSum(solver.MakeProd(rabbits, 4), solver.MakeProd(pheasants, 2));
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Constraint* const c1 = solver.MakeEquality(legs, 56);
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solver.AddConstraint(c1);
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DecisionBuilder* const db = solver.MakePhase(
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rabbits, pheasants,
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Solver::CHOOSE_FIRST_UNBOUND,
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Solver::ASSIGN_MIN_VALUE);
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bool has_result = solver.Solve(db);
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// Check that the problem has a solution.
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if (has_result != true) {
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LOG(FATAL) << "The problem does not have a solution!";
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}
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int count = 0;
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while (solver.NextSolution()) {
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count++;
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LOG(INFO) << "Solution " << count << ":";
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LOG(INFO) << "rabbits = " << rabbits->Value();
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LOG(INFO) << "pheasants = " << rabbits->Value();
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}
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LOG(INFO) << "Number of solutions: " << count;
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LOG(INFO) << "";
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LOG(INFO) << "Advanced usage:";
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LOG(INFO) << "Problem solved in " << solver.wall_time() << " milliseconds";
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}
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} // namespace operations_research
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int main(int argc, char **argv) {
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google::InitGoogleLogging(argv[0]);
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FLAGS_logtostderr = 1;
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operations_research::RunConstraintProgrammingExample();
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return 0;
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}
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