# Copyright 2010 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.
"""
Grocery problem in Google CP Solver.
From Christian Schulte, Gert Smolka, Finite Domain
http://www.mozart-oz.org/documentation/fdt/
Constraint Programming in Oz. A Tutorial. 2001.
'''
A kid goes into a grocery store and buys four items. The cashier
charges $7.11, the kid pays and is about to leave when the cashier
calls the kid back, and says 'Hold on, I multiplied the four items
instead of adding them; I'll try again; Hah, with adding them the
price still comes to $7.11'. What were the prices of the four items?
'''
Compare with the following models:
* MiniZinc: http://hakank.org/minizinc/grocery.mzn
* Comet: http://hakank.org/comet/grocery.co
* Zinc: http://hakank.org/minizinc/grocery.zinc
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/
"""
import sys
import string
from ortools.constraint_solver import pywrapcp
def main():
# Create the solver.
solver = pywrapcp.Solver("Grocery")
#
# data
#
n = 4
c = 711
#
# declare variables
#
item = [solver.IntVar(0, c, "item[%i]" % i) for i in range(n)]
#
# constraints
#
solver.Add(solver.Sum(item) == c)
solver.Add(reduce(lambda x, y: x * y, item) == c * 100 ** 3)
# symmetry breaking
for i in range(1, n):
solver.Add(item[i - 1] < item[i])
#
# search and result
#
db = solver.Phase(item,
solver.INT_VAR_SIMPLE,
solver.INT_VALUE_SIMPLE)
solver.NewSearch(db)
num_solutions = 0
while solver.NextSolution():
print "item:", [item[i].Value() for i in range(n)]
print
num_solutions += 1
solver.EndSearch()
print
print "num_solutions:", num_solutions
print "failures:", solver.Failures()
print "branches:", solver.Branches()
print "WallTime:", solver.WallTime()
if __name__ == "__main__":
main()