112 lines
3.3 KiB
Python
112 lines
3.3 KiB
Python
# Copyright 2010 Hakan Kjellerstrand hakank@bonetmail.com
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#
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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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"""
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xkcd problem (Knapsack) in Google CP Solver.
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http://xkcd.com/287/
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Some amount (or none) of each dish should be ordered to give a total
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of exact 15.05
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Compare with the following models:
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* Comet: http://www.hakank.org/comet/xkcd.co
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* ECLiPSE: http://www.hakank.org/eclipse/xkcd.ecl
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* Gecode: http://www.hakank.org/gecode/xkcd.cpp
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* Gecode/R: http://www.hakank.org/gecode_r/xkcd.rb
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* MiniZinc: http://www.hakank.org/minizinc/xkcd.mzn
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* Tailor: http://www.hakank.org/minizinc/xkcd.mzn
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* SICtus: http://www.hakank.org/sicstus/xkcd.pl
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* Zinc: http://www.hakank.org/minizinc/xkcd.zinc
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This model was created by Hakan Kjellerstrand (hakank@bonetmail.com)
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Also see my other Google CP Solver models: http://www.hakank.org/google_cp_solver/
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"""
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from ortools.constraint_solver import pywrapcp
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def main():
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# Create the solver.
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solver = pywrapcp.Solver('xkcd knapsack')
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#
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# data
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#
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num_prices = 6
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# for price and total: multiplied by 100 to be able to use integers
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price = [215, 275, 335, 355, 420, 580]
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total = 1505
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products = ["mixed fruit", "french fries", "side salad",
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"host wings", "mozzarella sticks", "samples place"]
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# declare variables
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# how many items of each dish
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x = [solver.IntVar(0,10, 'x%i' % i) for i in range(num_prices)]
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z = solver.IntVar(0,1505,'z')
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#
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# constraints
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#
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solver.Add(z == solver.Sum([x[i]*price[i] for i in range(num_prices)] ))
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solver.Add(z == total)
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#
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# solution and search
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#
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solution = solver.Assignment()
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solution.Add([x[i] for i in range(num_prices)])
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solution.Add(z)
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collector = solver.AllSolutionCollector(solution)
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# collector = solver.FirstSolutionCollector(solution)
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# search_log = solver.SearchLog(100, x[0])
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solver.Solve(solver.Phase([x[i] for i in range(num_prices)],
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solver.INT_VAR_SIMPLE,
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solver.ASSIGN_MIN_VALUE),
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[collector])
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num_solutions = collector.SolutionCount()
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print "num_solutions: ", num_solutions
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if num_solutions > 0:
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for s in range(num_solutions):
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print "z:", collector.Value(s, z)
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xval = [collector.Value(s, x[i]) for i in range(num_prices)]
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print "x:", xval
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for i in range(num_prices):
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if xval[i] > 0:
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print xval[i], "of", products[i], ":", price[i]/100.0
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print
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print
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print "num_solutions:", num_solutions
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print "failures:", solver.Failures()
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print "branches:", solver.Branches()
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print "WallTime:", solver.WallTime()
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else:
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print "No solutions found"
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if __name__ == '__main__':
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main()
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