65 lines
2.4 KiB
C++
65 lines
2.4 KiB
C++
// Copyright 2010-2025 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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//
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// Function for outputting an assignment problem in DIMACS format:
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// http://lpsolve.sourceforge.net/5.5/DIMACS_asn.htm
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//
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#ifndef OR_TOOLS_EXAMPLES_PRINT_DIMACS_ASSIGNMENT_H_
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#define OR_TOOLS_EXAMPLES_PRINT_DIMACS_ASSIGNMENT_H_
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#include <cstdio>
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#include <string>
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#include "absl/strings/str_format.h"
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#include "absl/strings/string_view.h"
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#include "ortools/base/file.h"
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#include "ortools/base/helpers.h"
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#include "ortools/base/logging.h"
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#include "ortools/base/options.h"
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#include "ortools/graph/linear_assignment.h"
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namespace operations_research {
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// Given a LinearSumAssignment object representing an assignment problem
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// description, outputs the problem in DIMACS format in the output file.
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// For a description of the format, see
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// http://lpsolve.sourceforge.net/5.5/DIMACS_asn.htm
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template <typename GraphType>
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void PrintDimacsAssignmentProblem(
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const LinearSumAssignment<GraphType>& assignment,
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absl::string_view output_filename) {
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File* output;
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CHECK_OK(file::Open(output_filename, "w", &output, file::Defaults()));
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const GraphType& graph(assignment.Graph());
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std::string output_line =
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absl::StrFormat("p asn %d %d\n", graph.num_nodes(), graph.num_arcs());
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CHECK_OK(file::WriteString(output, output_line, file::Defaults()));
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for (const typename GraphType::NodeIndex left_node :
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assignment.BipartiteLeftNodes()) {
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output_line = absl::StrFormat("n %d\n", left_node + 1);
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CHECK_OK(file::WriteString(output, output_line, file::Defaults()));
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}
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for (const auto& arc : graph.AllForwardArcs()) {
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output_line = absl::StrFormat("a %d %d %d\n", graph.Tail(arc) + 1,
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graph.Head(arc) + 1, assignment.ArcCost(arc));
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CHECK_OK(file::WriteString(output, output_line, file::Defaults()));
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}
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}
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} // namespace operations_research
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#endif // OR_TOOLS_EXAMPLES_PRINT_DIMACS_ASSIGNMENT_H_
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