133 lines
3.1 KiB
Python
133 lines
3.1 KiB
Python
# Copyright 2010 Hakan Kjellerstrand hakank@gmail.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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Place number puzzle Google CP Solver.
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http://ai.uwaterloo.ca/~vanbeek/Courses/Slides/introduction.pdf
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'''
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Place numbers 1 through 8 on nodes
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- each number appears exactly once
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- no connected nodes have consecutive numbers
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2 - 5
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/ | X | \
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1 - 3 - 6 - 8
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\ | X | /
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4 - 7
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""
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Compare with the following models:
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* MiniZinc: http://www.hakank.org/minizinc/place_number.mzn
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* Comet: http://www.hakank.org/comet/place_number_puzzle.co
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* ECLiPSe: http://www.hakank.org/eclipse/place_number_puzzle.ecl
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* SICStus Prolog: http://www.hakank.org/sicstus/place_number_puzzle.pl
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* Gecode: http://www.hakank.org/gecode/place_number_puzzle.cpp
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This model was created by Hakan Kjellerstrand (hakank@gmail.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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from __future__ import print_function
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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("Place number")
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# data
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m = 32
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n = 8
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# Note: this is 1-based for compatibility (and lazyness)
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graph = [
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[1, 2],
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[1, 3],
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[1, 4],
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[2, 1],
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[2, 3],
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[2, 5],
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[2, 6],
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[3, 2],
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[3, 4],
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[3, 6],
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[3, 7],
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[4, 1],
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[4, 3],
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[4, 6],
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[4, 7],
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[5, 2],
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[5, 3],
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[5, 6],
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[5, 8],
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[6, 2],
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[6, 3],
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[6, 4],
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[6, 5],
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[6, 7],
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[6, 8],
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[7, 3],
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[7, 4],
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[7, 6],
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[7, 8],
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[8, 5],
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[8, 6],
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[8, 7]
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]
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# declare variables
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x = [solver.IntVar(1, n, "x%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.AllDifferent(x))
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for i in range(m):
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# Note: make 0-based
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solver.Add(abs(
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x[graph[i][0] - 1] - x[graph[i][1] - 1]) > 1)
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# symmetry breaking
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solver.Add(x[0] < x[n - 1])
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#
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# solution and search
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#
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solution = solver.Assignment()
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solution.Add(x)
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collector = solver.AllSolutionCollector(solution)
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solver.Solve(solver.Phase(x,
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solver.CHOOSE_FIRST_UNBOUND,
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solver.ASSIGN_MIN_VALUE),
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[collector])
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num_solutions = collector.SolutionCount()
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for s in range(num_solutions):
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print("x:", [collector.Value(s, x[i]) for i in range(len(x))])
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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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print()
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if __name__ == "__main__":
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main()
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