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* Copyright (c) 1999-2014, Ecole des Mines de Nantes
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* modification, are permitted provided that the following conditions are met:
*
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* documentation and/or other materials provided with the distribution.
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* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
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package samples.pert;
import org.kohsuke.args4j.Option;
import samples.AbstractProblem;
import solver.ResolutionPolicy;
import solver.Solver;
import solver.constraints.Constraint;
import solver.constraints.IntConstraintFactory;
import solver.search.strategy.IntStrategyFactory;
import solver.variables.IntVar;
import solver.variables.VariableFactory;
import java.util.ArrayDeque;
import java.util.BitSet;
import java.util.Deque;
/**
* <br/>
*
* @author Charles Prud'homme
* @since 31/03/11
*/
public class Pert extends AbstractProblem {
@Option(name = "-n", usage = "Number of nodes.", required = false)
int n = 1000;
@Option(name = "-l", usage = "Number of layers.", required = false)
int layers = 200;
@Option(name = "-d", usage = "Number of layers in disjunction.", required = false)
int disjunctions = 2;
int horizon;
IntVar[] vars;
int[][] graph;
BitSet[] alldiffLayers = new BitSet[0];
protected void setUp() {
GraphGenerator2 generator = new GraphGenerator2(layers, n, disjunctions, seed);
generator.generate();
this.graph = generator.getGraph();
this.horizon = n - 1;
}
@Override
public void createSolver() {
solver = new Solver("Pert");
}
@Override
public void buildModel() {
setUp();
vars = VariableFactory.boundedArray("task", n, 0, horizon, solver);
for (int i = 0; i < n - 1; i++) {
for (int j = i + 1; j < n; j++) {
if (graph[i][j] == 1) {
solver.post(precedence(vars[i], 1, vars[j]));
}
}
}
for (int i = 0; i < alldiffLayers.length; i++) {
BitSet disjoint = alldiffLayers[i];
IntVar[] tvars = new IntVar[disjoint.cardinality()];
for (int k = 0, j = disjoint.nextSetBit(0); j >= 0; j = disjoint.nextSetBit(j + 1), k++) {
tvars[k] = vars[j];
}
solver.post(IntConstraintFactory.alldifferent(tvars, "BC"));
}
}
static Constraint precedence(IntVar x, int duration, IntVar y) {
return IntConstraintFactory.arithm(x, "<=", y, "-", duration);
}
@Override
public void configureSearch() {
solver.set(IntStrategyFactory.lexico_LB(vars));
int[] rank = new int[n];
boolean[] treated = new boolean[n];
int i = 0;
Deque<Integer> toTreat = new ArrayDeque<Integer>();
toTreat.push(i);
rank[i] = 0;
while (!toTreat.isEmpty()) {
i = toTreat.pop();
treated[i] = true;
for (int j = 0; j < n; j++) {
if (graph[i][j] == 1) {
rank[j] = Math.max(rank[i] + 1, rank[j]);
if (!treated[j] && !toTreat.contains(j)) {
toTreat.push(j);
}
}
}
}
}
@Override
public void solve() {
solver.findOptimalSolution(ResolutionPolicy.MINIMIZE, vars[n - 1]);
}
@Override
public void prettyOut() {
}
public static void main(String[] args) {
new Pert().execute(args);
}
}