e179c8b847
* remove python script * remove RTE actions * fix test_xpress_interface.cc * remove callback_xpress.py * revert writing colnames and rownames * accept suggestion from Mizux * clean * change cmake/README.md * try fix build bazel * try fix build bazel add MPSWriteError.h * xpress tests gracefully exit if Xpress not found * add integer and linear programming test for dotnet python and java * remove MPSWriteError * try fix Window build * remove useless line from CMakeLists.txt * try fix test under windows * reformat * use XPRESS_LP instead of XPRESS for linear programming examples * tools: add --platform arg when possible make script more resilient/cross-platform * [CP-SAT] convert to PEP8 convention * use XPRSmipoptimize and XPRSlpoptimize instead of XPRSminim and XPRSmaxim (#114) * use XPRSmipoptimize and XPRSlpoptimize instead of XPRSminim and XPRSmaxim * clean xpress/environment files * accept changes: empty char* parameter for XPRS*optimize * Add test on number iterations with LP basis * fix gtests flags * refactor * suggestions by @flomnes * remove unwanted files --------- Co-authored-by: Andrea Sgattoni <andrea.sgattoni@rte-france.com> Co-authored-by: Laurent Perron <lperron@google.com> Co-authored-by: Corentin Le Molgat <corentinl@google.com> Co-authored-by: Andrea Sgattoni <andrea.sgattoni@gmail.com>
101 lines
3.1 KiB
Python
101 lines
3.1 KiB
Python
#!/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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"""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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see: https://en.wikipedia.org/wiki/Golomb_ruler
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"""
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from typing import Sequence
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from absl import app
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from absl import flags
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from google.protobuf import text_format
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from ortools.sat.python import cp_model
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_ORDER = flags.DEFINE_integer("order", 8, "Order of the ruler.")
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_PARAMS = flags.DEFINE_string(
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"params",
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"num_search_workers:16,log_search_progress:true,max_time_in_seconds:45",
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"Sat solver parameters.",
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)
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def solve_golomb_ruler(order: int, params: str):
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"""Solve the Golomb ruler problem."""
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# Create the model.
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model = cp_model.CpModel()
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var_max = order * order
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all_vars = list(range(0, order))
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marks = [model.new_int_var(0, var_max, f"marks_{i}") for i in all_vars]
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model.add(marks[0] == 0)
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for i in range(order - 2):
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model.add(marks[i + 1] > marks[i])
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diffs = []
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for i in range(order - 1):
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for j in range(i + 1, order):
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diff = model.new_int_var(0, var_max, f"diff [{j},{i}]")
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model.add(diff == marks[j] - marks[i])
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diffs.append(diff)
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model.add_all_different(diffs)
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# symmetry breaking
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if order > 2:
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model.add(marks[order - 1] - marks[order - 2] > marks[1] - marks[0])
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# Objective
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model.minimize(marks[order - 1])
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# Solve the model.
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solver = cp_model.CpSolver()
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if params:
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text_format.Parse(params, solver.parameters)
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solution_printer = cp_model.ObjectiveSolutionPrinter()
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print(f"Golomb ruler(order={order})")
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status = solver.solve(model, solution_printer)
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# Print solution.
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print(f"status: {solver.status_name(status)}")
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if status in (cp_model.OPTIMAL, cp_model.FEASIBLE):
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for idx, var in enumerate(marks):
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print(f"mark[{idx}]: {solver.value(var)}")
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intervals = [solver.value(diff) for diff in diffs]
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intervals.sort()
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print(f"intervals: {intervals}")
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print("Statistics:")
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print(f"- conflicts: {solver.num_conflicts}")
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print(f"- branches : {solver.num_branches}")
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print(f"- wall time: {solver.wall_time}s\n")
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def main(argv: Sequence[str]) -> None:
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if len(argv) > 1:
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raise app.UsageError("Too many command-line arguments.")
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solve_golomb_ruler(_ORDER.value, _PARAMS.value)
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if __name__ == "__main__":
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app.run(main)
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