c34026b101
note: done using ```sh git grep -l "2010-2024 Google" | xargs sed -i 's/2010-2024 Google/2010-2025 Google/' ```
76 lines
2.4 KiB
C++
76 lines
2.4 KiB
C++
// Copyright 2010-2025 Google LLC
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// [START program]
|
|
// From Taha 'Introduction to Operations Research', example 6.4-2."""
|
|
// [START import]
|
|
#include <cstddef>
|
|
#include <cstdint>
|
|
#include <vector>
|
|
|
|
#include "ortools/graph/max_flow.h"
|
|
// [END import]
|
|
|
|
namespace operations_research {
|
|
// MaxFlow simple interface example.
|
|
void SimpleMaxFlowProgram() {
|
|
// [START solver]
|
|
// Instantiate a SimpleMaxFlow solver.
|
|
SimpleMaxFlow max_flow;
|
|
// [END solver]
|
|
|
|
// [START data]
|
|
// Define three parallel arrays: start_nodes, end_nodes, and the capacities
|
|
// between each pair. For instance, the arc from node 0 to node 1 has a
|
|
// capacity of 20.
|
|
std::vector<int64_t> start_nodes = {0, 0, 0, 1, 1, 2, 2, 3, 3};
|
|
std::vector<int64_t> end_nodes = {1, 2, 3, 2, 4, 3, 4, 2, 4};
|
|
std::vector<int64_t> capacities = {20, 30, 10, 40, 30, 10, 20, 5, 20};
|
|
// [END data]
|
|
|
|
// [START constraints]
|
|
// Add each arc.
|
|
for (int i = 0; i < start_nodes.size(); ++i) {
|
|
max_flow.AddArcWithCapacity(start_nodes[i], end_nodes[i], capacities[i]);
|
|
}
|
|
// [END constraints]
|
|
|
|
// [START solve]
|
|
// Find the maximum flow between node 0 and node 4.
|
|
int status = max_flow.Solve(0, 4);
|
|
// [END solve]
|
|
|
|
// [START print_solution]
|
|
if (status == SimpleMaxFlow::OPTIMAL) {
|
|
LOG(INFO) << "Max flow: " << max_flow.OptimalFlow();
|
|
LOG(INFO) << "";
|
|
LOG(INFO) << " Arc Flow / Capacity";
|
|
for (std::size_t i = 0; i < max_flow.NumArcs(); ++i) {
|
|
LOG(INFO) << max_flow.Tail(i) << " -> " << max_flow.Head(i) << " "
|
|
<< max_flow.Flow(i) << " / " << max_flow.Capacity(i);
|
|
}
|
|
} else {
|
|
LOG(INFO) << "Solving the max flow problem failed. Solver status: "
|
|
<< status;
|
|
}
|
|
// [END print_solution]
|
|
}
|
|
|
|
} // namespace operations_research
|
|
|
|
int main() {
|
|
operations_research::SimpleMaxFlowProgram();
|
|
return EXIT_SUCCESS;
|
|
}
|
|
// [END program]
|