80 lines
2.5 KiB
Python
80 lines
2.5 KiB
Python
# Copyright 2010-2018 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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"""Integer programming examples that show how to use the APIs."""
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# [START program]
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# [START import]
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from __future__ import print_function
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from ortools.linear_solver import pywraplp
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# [END import]
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def main():
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# [START solver]
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# Create the mip solver with the CBC backend.
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solver = pywraplp.Solver('simple_mip_program',
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pywraplp.Solver.CBC_MIXED_INTEGER_PROGRAMMING)
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# [END solver]
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# [START variables]
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infinity = solver.infinity()
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# x and y are integer non-negative variables.
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x = solver.IntVar(0.0, infinity, 'x')
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y = solver.IntVar(0.0, infinity, 'y')
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print('Number of variables = ', solver.NumVariables())
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# [END variables]
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# [START constraints]
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# x + 7 * y <= 17.5.
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solver.Add(x + 7 * y <= 17.5)
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# x <= 3.5.
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solver.Add(x <= 3.5)
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print('Number of constraints = ', solver.NumConstraints())
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# [END constraints]
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# [START objective]
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# Maximize x + 10 * y.
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solver.Maximize(x + 10 * y)
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# [END objective]
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# [START solve]
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result_status = solver.Solve()
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# The problem has an optimal solution.
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assert result_status == pywraplp.Solver.OPTIMAL
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# The solution looks legit (when using solvers others than
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# GLOP_LINEAR_PROGRAMMING, verifying the solution is highly recommended!).
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assert solver.VerifySolution(1e-7, True)
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# [END solve]
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# [START print_solution]
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print('Solution:')
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print('Objective value = ', solver.Objective().Value())
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print('x = ', x.solution_value())
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print('y = ', y.solution_value())
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# [END print_solution]
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# [START advanced]
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print('\nAdvanced usage:')
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print('Problem solved in %f milliseconds' % solver.wall_time())
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print('Problem solved in %d iterations' % solver.iterations())
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print('Problem solved in %d branch-and-bound nodes' % solver.nodes())
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# [END advanced]
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if __name__ == '__main__':
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main()
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# [END program]
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