109 lines
3.3 KiB
Python
Executable File
109 lines
3.3 KiB
Python
Executable File
#!/usr/bin/env python3
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# Copyright 2010-2022 Google LLC
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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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# [START program]
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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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# [START import]
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from ortools.sat.python import cp_model
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# [END import]
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# [START solution_printer]
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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 on_solution_callback(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 solution_count(self):
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return self.__solution_count
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# [END solution_printer]
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def main():
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"""Solve the CP+IS+FUN==TRUE cryptarithm."""
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# Constraint programming engine
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# [START model]
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model = cp_model.CpModel()
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# [END model]
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# [START variables]
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base = 10
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c = model.NewIntVar(1, base - 1, 'C')
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p = model.NewIntVar(0, base - 1, 'P')
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i = model.NewIntVar(1, base - 1, 'I')
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s = model.NewIntVar(0, base - 1, 'S')
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f = model.NewIntVar(1, base - 1, 'F')
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u = model.NewIntVar(0, base - 1, 'U')
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n = model.NewIntVar(0, base - 1, 'N')
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t = model.NewIntVar(1, base - 1, 'T')
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r = model.NewIntVar(0, base - 1, 'R')
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e = model.NewIntVar(0, base - 1, '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 base >= len(letters)
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# [END variables]
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# Define constraints.
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# [START constraints]
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model.AddAllDifferent(letters)
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# CP + IS + FUN = TRUE
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model.Add(c * base + p + i * base + s + f * base * base + u * base +
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n == t * base * base * base + r * base * base + u * base + e)
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# [END constraints]
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# Creates a solver and solves the model.
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# [START solve]
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solver = cp_model.CpSolver()
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solution_printer = VarArraySolutionPrinter(letters)
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# Enumerate all solutions.
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solver.parameters.enumerate_all_solutions = True
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# Solve.
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status = solver.Solve(model, solution_printer)
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# [END solve]
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# Statistics.
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# [START statistics]
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print('\nStatistics')
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print(f' status : {solver.StatusName(status)}')
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print(f' conflicts: {solver.NumConflicts()}')
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print(f' branches : {solver.NumBranches()}')
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print(f' wall time: {solver.WallTime()} s')
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print(f' sol found: {solution_printer.solution_count()}')
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# [END statistics]
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if __name__ == '__main__':
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main()
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# [END program]
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