# Copyright 2011 Hakan Kjellerstrand hakank@bonetmail.com
#
# 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.
"""
Volsay problem in Google or-tools.
From the OPL model volsay.mod
This model was created by Hakan Kjellerstrand (hakank@bonetmail.com)
Also see my other Google CP Solver models:
http://www.hakank.org/google_or_tools/
"""
from ortools.linear_solver import pywraplp
def main(unused_argv):
# Create the solver.
# using GLPK
solver = pywraplp.Solver('CoinsGridGLPK',
pywraplp.Solver.GLPK_LINEAR_PROGRAMMING)
# Using CLP
# solver = pywraplp.Solver('CoinsGridCLP',
# pywraplp.Solver.CLP_LINEAR_PROGRAMMING)
# data
# declare variables
Gas = solver.NumVar(0, 100000, 'Gas')
Chloride = solver.NumVar(0, 100000, 'Cloride')
#
# constraints
#
solver.Add(Gas + Chloride <= 50)
solver.Add(3 * Gas + 4 * Chloride <= 180)
# objective
objective = solver.Maximize(40 * Gas + 50 * Chloride)
print 'NumConstraints:', solver.NumConstraints()
#
# solution and search
#
solver.Solve()
print
print 'objective = ', solver.Objective().Value()
print 'Gas = ', Gas.SolutionValue(), 'ReducedCost =', Gas.ReducedCost()
print 'Chloride:', Chloride.SolutionValue(), 'ReducedCost =', Chloride.ReducedCost()
if __name__ == '__main__':
main('Volsay')