1# Copyright 2011 Hakan Kjellerstrand hakank@gmail.com 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); 4# you may not use this file except in compliance with the License. 5# You may obtain a copy of the License at 6# 7# http://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, 11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12# See the License for the specific language governing permissions and 13# limitations under the License. 14""" 15 16 Volsay problem in Google or-tools. 17 18 From the OPL model volsay.mod 19 20 This model was created by Hakan Kjellerstrand (hakank@gmail.com) 21 Also see my other Google CP Solver models: 22 http://www.hakank.org/google_or_tools/ 23""" 24from ortools.linear_solver import pywraplp 25 26 27def main(unused_argv): 28 29 # Create the solver. 30 31 # using GLPK 32 #solver = pywraplp.Solver('CoinsGridGLPK', 33 # pywraplp.Solver.GLPK_LINEAR_PROGRAMMING) 34 35 # Using CLP 36 solver = pywraplp.Solver('CoinsGridCLP', 37 pywraplp.Solver.CLP_LINEAR_PROGRAMMING) 38 39 # data 40 41 # declare variables 42 Gas = solver.NumVar(0, 100000, 'Gas') 43 Chloride = solver.NumVar(0, 100000, 'Cloride') 44 45 # 46 # constraints 47 # 48 solver.Add(Gas + Chloride <= 50) 49 solver.Add(3 * Gas + 4 * Chloride <= 180) 50 51 # objective 52 objective = solver.Maximize(40 * Gas + 50 * Chloride) 53 54 print('NumConstraints:', solver.NumConstraints()) 55 56 # 57 # solution and search 58 # 59 solver.Solve() 60 61 print() 62 print('objective = ', solver.Objective().Value()) 63 print('Gas = ', Gas.SolutionValue(), 'ReducedCost =', Gas.ReducedCost()) 64 print('Chloride:', Chloride.SolutionValue(), 'ReducedCost =', 65 Chloride.ReducedCost()) 66 67 68if __name__ == '__main__': 69 main('Volsay') 70