90 lines
2.8 KiB
Python
90 lines
2.8 KiB
Python
# 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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"""Cryptarithmetic 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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"""
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from __future__ import print_function
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from ortools.sat.python import cp_model
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class VarArraySolutionPrinter(cp_model.CpSolverSolutionCallback):
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"""Print intermediate solutions."""
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def __init__(self, variables):
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cp_model.CpSolverSolutionCallback.__init__(self)
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self.__variables = variables
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self.__solution_count = 0
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def OnSolutionCallback(self):
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self.__solution_count += 1
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for v in self.__variables:
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print('%s=%i' % (v, self.Value(v)), end=' ')
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print()
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def SolutionCount(self):
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return self.__solution_count
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def CPIsFun():
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kBase = 10
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# Constraint programming engine
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model = cp_model.CpModel()
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c = model.NewIntVar(1, 9, 'C')
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p = model.NewIntVar(0, 9, 'P')
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i = model.NewIntVar(1, 9, 'I')
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s = model.NewIntVar(0, 9, 'S')
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f = model.NewIntVar(1, 9, 'F')
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u = model.NewIntVar(0, 9, 'U')
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n = model.NewIntVar(0, 9, 'N')
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t = model.NewIntVar(1, 9, 'T')
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r = model.NewIntVar(0, 9, 'R')
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e = model.NewIntVar(0, 9, 'E')
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# We need to group variables in a list to use the constraint AllDifferent.
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letters = [c, p, i, s, f, u, n, t, r, e]
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# Verify that we have enough digits.
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assert kBase >= len(letters)
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# Define constraints.
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model.AddAllDifferent(letters)
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# CP + IS + FUN = TRUE
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model.Add(p + s + n + kBase * (c + i + u) + kBase * kBase * f == e +
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kBase * u + kBase * kBase * r + kBase * kBase * kBase * t)
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### Solve model.
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solver = cp_model.CpSolver()
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solution_printer = VarArraySolutionPrinter(letters)
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status = solver.SearchForAllSolutions(model, solution_printer)
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print()
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print('Statistics')
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print(' - status : %s' % solver.StatusName(status))
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print(' - conflicts : %i' % solver.NumConflicts())
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print(' - branches : %i' % solver.NumBranches())
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print(' - wall time : %f ms' % solver.WallTime())
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print(' - solutions found : %i' % solution_printer.SolutionCount())
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if __name__ == '__main__':
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CPIsFun()
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