83 lines
2.6 KiB
Python
83 lines
2.6 KiB
Python
# Copyright 2010-2013 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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"""This is the Golomb ruler problem.
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This model aims at maximizing radar interferences in a minimum space.
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It is known as the Golomb Ruler problem.
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The idea is to put marks on a rule such that all differences
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between all marks are all different. The objective is to minimize the length
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of the rule.
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"""
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from google.apputils import app
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import gflags
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from constraint_solver import pywrapcp
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FLAGS = gflags.FLAGS
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# We disable the following warning because it is a false positive on constraints
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# like: solver.Add(x == 0)
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# pylint: disable-msg=C6403
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def main(unused_argv):
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# Create the solver.
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solver = pywrapcp.Solver('golomb ruler')
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size = 8
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var_max = size * size
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all_vars = range(0, size)
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marks = [solver.IntVar(0, var_max, 'marks_%d' % i) for i in all_vars]
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objective = solver.Minimize(marks[size - 1], 1)
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solver.Add(marks[0] == 0)
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solver.Add(solver.AllDifferent([marks[j] - marks[i]
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for i in range(0, size - 1)
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for j in range(i +1, size)]))
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solver.Add(marks[size - 1] - marks[size - 2] > marks[1] - marks[0])
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for i in range(0, size - 2):
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solver.Add(marks[i + 1] > marks[i])
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solution = solver.Assignment()
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solution.Add(marks[size - 1])
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collector = solver.AllSolutionCollector(solution)
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solver.Solve(solver.Phase(marks,
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solver.CHOOSE_FIRST_UNBOUND,
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solver.ASSIGN_MIN_VALUE),
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[objective, collector])
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for i in range(0, collector.SolutionCount()):
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obj_value = collector.Value(i, marks[size -1])
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time = collector.WallTime(i)
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branches = collector.Branches(i)
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failures = collector.Failures(i)
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print ('Solution #%i: value = %i, failures = %i, branches = %i,'
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'time = %i ms') % (i, obj_value, failures, branches, time)
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time = solver.WallTime()
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branches = solver.Branches()
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failures = solver.Failures()
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print ('Total run : failures = %i, branches = %i, time = %i ms' %
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(failures, branches, time))
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if __name__ == '__main__':
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app.run()
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