private void explore(
int vidx,
int sum,
int[] path,
IntegerVariable[] vars,
int[] coeffs,
int goal,
List<int[]> ts) {
if (vidx == vars.length) {
if (sum == goal) {
ts.add(path.clone());
}
return;
}
DisposableIntIterator it = vars[vidx].getDomainIterator();
while (it.hasNext()) {
path[vidx] = it.next();
explore(vidx + 1, sum + coeffs[vidx] * path[vidx], path, vars, coeffs, goal, ts);
}
it.dispose();
}
/**
* all the arc (u,v), such that v belongs to the set depicted by the iterator, are removed
*
* @param u index of a node
* @param deltaDomain an iterator over the removed indices
*/
public void remAllNodes(int u, DisposableIntIterator deltaDomain) {
while (deltaDomain.hasNext()) {
int v = deltaDomain.next();
graph[u].set(v, false);
revGraph[v].set(u, false);
}
deltaDomain.dispose();
while (deltaDomain.hasNext()) {
int v = deltaDomain.next();
if (params.contains(Maintain.TRANSITIVE_CLOSURE)) remIncreTC(u, v);
}
deltaDomain.dispose();
if (params.contains(Maintain.TRANSITIVE_REDUCTION)) computeTRfromScratch();
updateSpecialNodes();
if (params.contains(Maintain.CONNECTED_COMP)) computeCCfromScratch();
}
/**
* @param vars Boolean variables
* @param goal Sum
* @param coeffs An array Containing the coefficients
* @return
*/
public SConstraint knapsack(Solver s, IntegerVariable[] vars, int goal, int[] coeffs) {
boolean tuples = false;
int n = coeffs.length;
// first check bounds, coefficients and goal
if (goal < 0) {
tuples = true;
}
for (int i = 0; !tuples && i < n; i++) {
if (coeffs[i] < 0 || vars[i].getLowB() * coeffs[i] < 0 || vars[i].getUppB() * coeffs[i] < 0) {
tuples = true;
}
}
if (tuples) {
List<int[]> ts = new ArrayList<int[]>();
explore(0, 0, new int[vars.length], vars, coeffs, goal, ts);
if (ts.size() == 0) {
return Constant.FALSE; // not satisfiable
}
DFA dfa = new DFA(ts);
return new Regular(dfa, s.getVar(vars), s.getEnvironment());
} else {
int[] temp = new int[coeffs.length + 1];
System.arraycopy(coeffs, 0, temp, 1, coeffs.length);
temp[0] = 0;
coeffs = temp;
int[][] P = new int[coeffs.length][goal + 1];
int[][] G = new int[coeffs.length][goal + 1]; // table containing minimum solution paths
for (int i = 0; i < P.length; ++i)
for (int j = 0; j < P[0].length; ++j) P[i][j] = G[i][j] = 0;
P[0][0] = 1;
for (int i = 1; i < P.length; ++i)
for (int b = 0; b < goal + 1; ++b)
if (P[i - 1][b] == 1) {
DisposableIntIterator it = vars[i - 1].getDomainIterator();
while (it.hasNext()) {
int value = it.next();
// for (int x = bools[i - 1].getLowB(); x <= bools[i - 1].getUppB(); ++x)
if (b + coeffs[i] * value <= goal) P[i][b + coeffs[i] * value] = 1;
}
it.dispose();
}
boolean sat = false;
for (int i = goal; i >= goal; --i) sat |= (P[P.length - 1][goal] == 1);
G[G.length - 1][goal] = 1;
if (sat) {
for (int i = G.length - 2; i >= 0; --i)
for (int b = 0; b < G[0].length; b++)
if (G[i + 1][b] == 1) {
DisposableIntIterator it = vars[i].getDomainIterator();
while (it.hasNext()) {
int x = it.next();
// for (int x = bools[i].getLowB(); x <= bools[i].getUppB(); ++x)
if (b - coeffs[i + 1] * x >= 0 && P[i][b - coeffs[i + 1] * x] == 1)
G[i][b - coeffs[i + 1] * x] = 1;
}
it.dispose();
}
List<Transition> t = new LinkedList<Transition>();
List<Integer> ints = new LinkedList<Integer>();
nID = 0;
int[][] labels = new int[coeffs.length][goal + 1];
for (int i = 0; i < labels.length; ++i) {
Arrays.fill(labels[i], -1);
}
generateTransitionList(0, 0, t, labels, coeffs, G, vars);
for (int i = 0; i <= 0; ++i) {
ints.add(G.length + i - 1);
}
DFA dfa = new DFA(t, ints, ints.get(0));
return new Regular(dfa, s.getVar(vars), s.getEnvironment());
} else {
return Constant.FALSE; // not satisfiable
}
}
}
