98 lines
2.8 KiB
Python
98 lines
2.8 KiB
Python
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# Copyright 2010-2011 Google
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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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Cryptoarithmetic puzzle
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First attempt to solve equation CP + IS + FUN = TRUE
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where each letter represents a unique digit.
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This problem has 72 different solutions in base 10.
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Use of SolutionCollectors.
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Use of Solve().
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"""
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from constraint_solver import pywrapcp
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from os import abort
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def CPIsFun():
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# Constraint programming engine
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solver = pywrapcp.Solver('CP is fun!');
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kBase = 10
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# Decision variables
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digits = range(0, kBase)
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digits_without_zero = digits[1:]
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c = solver.IntVar(digits_without_zero, 'C');
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p = solver.IntVar(digits, 'P');
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i = solver.IntVar(digits_without_zero, 'I');
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s = solver.IntVar(digits, 'S');
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f = solver.IntVar(digits_without_zero, 'F');
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u = solver.IntVar(digits, 'U');
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n = solver.IntVar(digits, 'N');
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t = solver.IntVar(digits_without_zero, 'T');
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r = solver.IntVar(digits, 'R');
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e = solver.IntVar(digits, 'E');
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# We need to group variables in a list to be able to use
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# the global constraint AllDifferent
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letters = [c, p, i, s, f, u, n, t, r, e]
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# Check if we have enough digits
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assert kBase >= len(letters)
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# Constraints
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solver.Add(solver.AllDifferent(letters))
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# CP + IS + FUN = TRUE
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term1 = solver.Sum([kBase*c, p])
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term2 = solver.Sum([kBase*i, s])
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term3 = solver.Sum([kBase*kBase*f, kBase*u, n])
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sum_terms = solver.Sum([term1, term2, term3])
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sum_value = solver.Sum([kBase*kBase*kBase*t, kBase*kBase*r, kBase*u, e])
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solver.Add(sum_terms == sum_value)
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all_solutions = solver.AllSolutionCollector()
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# Add the interesting variables to the SolutionCollector
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all_solutions.Add(c)
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all_solutions.Add(p)
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# Create the variable kBase * c + p
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v1 = solver.Sum([kBase * c, p])
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# Add it to the SolutionCollector
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all_solutions.Add(v1);
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db = solver.Phase(letters, solver.INT_VAR_DEFAULT,
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solver.INT_VALUE_DEFAULT)
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solver.Solve(db, all_solutions)
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# Retrieve the solutions
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numberSolutions = all_solutions.SolutionCount()
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print "Number of solutions: ", numberSolutions
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solution = solver.Assignment()
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for index in range(numberSolutions):
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solution = all_solutions.Solution(index)
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print "Solution found:"
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print "v1=" ,solution.Value(v1)
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return
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if __name__ == '__main__':
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CPIsFun()
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