c34026b101
note: done using ```sh git grep -l "2010-2024 Google" | xargs sed -i 's/2010-2024 Google/2010-2025 Google/' ```
96 lines
3.4 KiB
Java
96 lines
3.4 KiB
Java
// 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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// [START program]
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package com.google.ortools.graph.samples;
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// [START import]
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import com.google.ortools.Loader;
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import com.google.ortools.graph.MinCostFlow;
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import com.google.ortools.graph.MinCostFlowBase;
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// [END import]
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/** Minimal Assignment Min Flow. */
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public class AssignmentMinFlow {
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public static void main(String[] args) throws Exception {
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Loader.loadNativeLibraries();
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// [START solver]
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// Instantiate a SimpleMinCostFlow solver.
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MinCostFlow minCostFlow = new MinCostFlow();
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// [END solver]
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// [START data]
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// Define four parallel arrays: sources, destinations, capacities, and unit costs
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// between each pair.
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int[] startNodes =
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new int[] {0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 6, 7, 8};
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int[] endNodes =
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new int[] {1, 2, 3, 4, 5, 6, 7, 8, 5, 6, 7, 8, 5, 6, 7, 8, 5, 6, 7, 8, 9, 9, 9, 9};
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int[] capacities =
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new int[] {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
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int[] unitCosts = new int[] {
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0, 0, 0, 0, 90, 76, 75, 70, 35, 85, 55, 65, 125, 95, 90, 105, 45, 110, 95, 115, 0, 0, 0, 0};
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int source = 0;
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int sink = 9;
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int tasks = 4;
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// Define an array of supplies at each node.
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int[] supplies = new int[] {tasks, 0, 0, 0, 0, 0, 0, 0, 0, -tasks};
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// [END data]
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// [START constraints]
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// Add each arc.
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for (int i = 0; i < startNodes.length; ++i) {
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int arc = minCostFlow.addArcWithCapacityAndUnitCost(
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startNodes[i], endNodes[i], capacities[i], unitCosts[i]);
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if (arc != i) {
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throw new Exception("Internal error");
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}
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}
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// Add node supplies.
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for (int i = 0; i < supplies.length; ++i) {
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minCostFlow.setNodeSupply(i, supplies[i]);
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}
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// [END constraints]
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// [START solve]
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// Find the min cost flow.
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MinCostFlowBase.Status status = minCostFlow.solve();
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// [END solve]
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// [START print_solution]
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if (status == MinCostFlow.Status.OPTIMAL) {
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System.out.println("Total cost: " + minCostFlow.getOptimalCost());
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System.out.println();
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for (int i = 0; i < minCostFlow.getNumArcs(); ++i) {
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// Can ignore arcs leading out of source or into sink.
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if (minCostFlow.getTail(i) != source && minCostFlow.getHead(i) != sink) {
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// Arcs in the solution have a flow value of 1. Their start and end nodes
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// give an assignment of worker to task.
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if (minCostFlow.getFlow(i) > 0) {
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System.out.println("Worker " + minCostFlow.getTail(i) + " assigned to task "
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+ minCostFlow.getHead(i) + " Cost: " + minCostFlow.getUnitCost(i));
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}
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}
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}
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} else {
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System.out.println("Solving the min cost flow problem failed.");
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System.out.println("Solver status: " + status);
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}
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// [END print_solution]
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}
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private AssignmentMinFlow() {}
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}
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// [END program]
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