102 lines
2.5 KiB
Python
102 lines
2.5 KiB
Python
# Copyright 2011 Hakan Kjellerstrand hakank@gmail.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.
|
|
"""
|
|
|
|
Knapsack problem using MIP in Google or-tools.
|
|
|
|
From the OPL model knapsack.mod
|
|
|
|
This model was created by Hakan Kjellerstrand (hakank@gmail.com)
|
|
Also see my other Google CP Solver models:
|
|
http://www.hakank.org/google_or_tools/
|
|
"""
|
|
import sys
|
|
from ortools.linear_solver import pywraplp
|
|
|
|
|
|
def main(sol='CBC'):
|
|
|
|
# Create the solver.
|
|
print('Solver: ', sol)
|
|
solver = pywraplp.Solver.CreateSolver(sol)
|
|
if not solver:
|
|
return
|
|
|
|
#
|
|
# data
|
|
#
|
|
nb_items = 12
|
|
nb_resources = 7
|
|
items = list(range(nb_items))
|
|
resources = list(range(nb_resources))
|
|
|
|
capacity = [18209, 7692, 1333, 924, 26638, 61188, 13360]
|
|
value = [96, 76, 56, 11, 86, 10, 66, 86, 83, 12, 9, 81]
|
|
use = [[19, 1, 10, 1, 1, 14, 152, 11, 1, 1, 1, 1],
|
|
[0, 4, 53, 0, 0, 80, 0, 4, 5, 0, 0, 0],
|
|
[4, 660, 3, 0, 30, 0, 3, 0, 4, 90, 0, 0],
|
|
[7, 0, 18, 6, 770, 330, 7, 0, 0, 6, 0, 0],
|
|
[0, 20, 0, 4, 52, 3, 0, 0, 0, 5, 4, 0],
|
|
[0, 0, 40, 70, 4, 63, 0, 0, 60, 0, 4, 0],
|
|
[0, 32, 0, 0, 0, 5, 0, 3, 0, 660, 0, 9]]
|
|
|
|
max_value = max(capacity)
|
|
|
|
#
|
|
# variables
|
|
#
|
|
take = [solver.IntVar(0, max_value, 'take[%i]' % j) for j in items]
|
|
|
|
# total cost, to be maximized
|
|
z = solver.Sum([value[i] * take[i] for i in items])
|
|
|
|
#
|
|
# constraints
|
|
#
|
|
for r in resources:
|
|
solver.Add(solver.Sum([use[r][i] * take[i] for i in items]) <= capacity[r])
|
|
|
|
# objective
|
|
objective = solver.Maximize(z)
|
|
|
|
#
|
|
# solution and search
|
|
#
|
|
solver.Solve()
|
|
|
|
print()
|
|
print('z: ', int(solver.Objective().Value()))
|
|
|
|
print('take:', end=' ')
|
|
for i in items:
|
|
print(int(take[i].SolutionValue()), end=' ')
|
|
print()
|
|
|
|
print()
|
|
print('walltime :', solver.WallTime(), 'ms')
|
|
if sol == 'CBC':
|
|
print('iterations:', solver.Iterations())
|
|
|
|
|
|
if __name__ == '__main__':
|
|
|
|
sol = 'CBC'
|
|
if len(sys.argv) > 1:
|
|
sol = sys.argv[1]
|
|
if sol != 'GLPK' and sol != 'CBC':
|
|
print('Solver must be either GLPK or CBC')
|
|
sys.exit(1)
|
|
|
|
main(sol)
|