8927b03942
Some of these imports are not used. The rest of them only import string to use the string.atoi function. But string.atoi(s) on a string input is identical to just int(s). See the docs: "deprecated since 2.0".
95 lines
2.5 KiB
Python
95 lines
2.5 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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Grocery problem in Google CP Solver.
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From Christian Schulte, Gert Smolka, Finite Domain
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http://www.mozart-oz.org/documentation/fdt/
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Constraint Programming in Oz. A Tutorial. 2001.
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'''
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A kid goes into a grocery store and buys four items. The cashier
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charges $7.11, the kid pays and is about to leave when the cashier
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calls the kid back, and says 'Hold on, I multiplied the four items
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instead of adding them; I'll try again; Hah, with adding them the
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price still comes to $7.11'. What were the prices of the four items?
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'''
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Compare with the following models:
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* MiniZinc: http://hakank.org/minizinc/grocery.mzn
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* Comet: http://hakank.org/comet/grocery.co
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* Zinc: http://hakank.org/minizinc/grocery.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:
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http://www.hakank.org/google_or_tools/
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"""
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import sys
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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("Grocery")
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#
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# data
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#
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n = 4
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c = 711
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#
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# declare variables
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#
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item = [solver.IntVar(0, c, "item[%i]" % i) for i in range(n)]
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#
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# constraints
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#
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solver.Add(solver.Sum(item) == c)
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solver.Add(reduce(lambda x, y: x * y, item) == c * 100 ** 3)
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# symmetry breaking
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for i in range(1, n):
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solver.Add(item[i - 1] < item[i])
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#
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# search and result
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#
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db = solver.Phase(item,
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solver.INT_VAR_SIMPLE,
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solver.INT_VALUE_SIMPLE)
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solver.NewSearch(db)
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num_solutions = 0
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while solver.NextSolution():
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print "item:", [item[i].Value() for i in range(n)]
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print
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num_solutions += 1
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solver.EndSearch()
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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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if __name__ == "__main__":
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main()
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