/**
* Determines a maximum weighted independent set with respect to
* the interference and conflict edges of all nodes in a qnode.
- * TODO: This runs in n! in worst case. Use a heuristic iff n>???
*/
static int ou_max_ind_set_costs(unit_t *ou) {
be_chordal_env_t *chordal_env = ou->co->chordal_env;
}
-
- /* now brute force the best set out of the unsafe nodes*/
- curr = bitset_alloca(unsafe_count);
-
- bitset_set_all(curr);
- while ((max = bitset_popcnt(curr)) != 0) {
- /* check if curr is a stable set */
- for (i=bitset_next_set(curr, 0); i!=-1; i=bitset_next_set(curr, i+1))
- for (o=bitset_next_set(curr, i+1); o!=-1; o=bitset_next_set(curr, o+1)) /* !!!!! difference to qnode_max_ind_set(): NOT (curr, i) */
- if (nodes_interfere(chordal_env, unsafe[i], unsafe[o]))
- goto no_stable_set;
-
- /* if we arrive here, we have a stable set */
- /* compute the weigth of the stable set*/
- curr_weight = 0;
- bitset_foreach(curr, pos)
- curr_weight += unsafe_costs[pos];
-
- /* any better ? */
- if (curr_weight > best_weight) {
- best_weight = curr_weight;
+ /* now compute the best set out of the unsafe nodes*/
+ if (unsafe_count > MIS_HEUR_TRIGGER) {
+ bitset_t *best = bitset_alloca(unsafe_count);
+ /* Heuristik: Greedy trial and error form index 0 to unsafe_count-1 */
+ for (i=0; i<unsafe_count; ++i) {
+ bitset_set(best, i);
+ /* check if it is a stable set */
+ for (o=bitset_next_set(best, 0); o!=-1 && o<i; o=bitset_next_set(best, o+1))
+ if (nodes_interfere(chordal_env, unsafe[i], unsafe[o])) {
+ bitset_clear(best, i); /* clear the bit and try next one */
+ break;
+ }
}
+ /* compute the weight */
+ bitset_foreach(best, pos)
+ best_weight += unsafe_costs[pos];
+ } else {
+ /* Exact Algorithm: Brute force */
+ curr = bitset_alloca(unsafe_count);
+ bitset_set_all(curr);
+ while ((max = bitset_popcnt(curr)) != 0) {
+ /* check if curr is a stable set */
+ for (i=bitset_next_set(curr, 0); i!=-1; i=bitset_next_set(curr, i+1))
+ for (o=bitset_next_set(curr, i+1); o!=-1; o=bitset_next_set(curr, o+1)) /* !!!!! difference to qnode_max_ind_set(): NOT (curr, i) */
+ if (nodes_interfere(chordal_env, unsafe[i], unsafe[o]))
+ goto no_stable_set;
+
+ /* if we arrive here, we have a stable set */
+ /* compute the weigth of the stable set*/
+ curr_weight = 0;
+ bitset_foreach(curr, pos)
+ curr_weight += unsafe_costs[pos];
+
+ /* any better ? */
+ if (curr_weight > best_weight) {
+ best_weight = curr_weight;
+ }
-no_stable_set:
- bitset_minus1(curr);
+ no_stable_set:
+ bitset_minus1(curr);
+ }
}
return safe_costs+best_weight;