0
4
0
... | ... |
@@ -131,15 +131,16 @@ |
131 | 131 |
|
132 | 132 |
private: |
133 | 133 |
|
134 | 134 |
TEMPLATE_DIGRAPH_TYPEDEFS(GR); |
135 | 135 |
|
136 | 136 |
typedef std::vector<int> IntVector; |
137 |
typedef std::vector<char> BoolVector; |
|
138 | 137 |
typedef std::vector<Value> ValueVector; |
139 | 138 |
typedef std::vector<Cost> CostVector; |
139 |
typedef std::vector<char> BoolVector; |
|
140 |
// Note: vector<char> is used instead of vector<bool> for efficiency reasons |
|
140 | 141 |
|
141 | 142 |
private: |
142 | 143 |
|
143 | 144 |
// Data related to the underlying digraph |
144 | 145 |
const GR &_graph; |
145 | 146 |
int _node_num; |
... | ... |
@@ -761,21 +762,21 @@ |
761 | 762 |
} |
762 | 763 |
} |
763 | 764 |
|
764 | 765 |
// Initialize delta value |
765 | 766 |
if (_factor > 1) { |
766 | 767 |
// With scaling |
767 |
Value max_sup = 0, max_dem = 0; |
|
768 |
for (int i = 0; i != _node_num; ++i) { |
|
768 |
Value max_sup = 0, max_dem = 0, max_cap = 0; |
|
769 |
for (int i = 0; i != _root; ++i) { |
|
769 | 770 |
Value ex = _excess[i]; |
770 | 771 |
if ( ex > max_sup) max_sup = ex; |
771 | 772 |
if (-ex > max_dem) max_dem = -ex; |
772 |
} |
|
773 |
Value max_cap = 0; |
|
774 |
for (int j = 0; j != _res_arc_num; ++j) { |
|
775 |
if (_res_cap[j] > max_cap) max_cap = _res_cap[j]; |
|
773 |
int last_out = _first_out[i+1] - 1; |
|
774 |
for (int j = _first_out[i]; j != last_out; ++j) { |
|
775 |
if (_res_cap[j] > max_cap) max_cap = _res_cap[j]; |
|
776 |
} |
|
776 | 777 |
} |
777 | 778 |
max_sup = std::min(std::min(max_sup, max_dem), max_cap); |
778 | 779 |
for (_delta = 1; 2 * _delta <= max_sup; _delta *= 2) ; |
779 | 780 |
} else { |
780 | 781 |
// Without scaling |
781 | 782 |
_delta = 1; |
... | ... |
@@ -194,16 +194,17 @@ |
194 | 194 |
|
195 | 195 |
private: |
196 | 196 |
|
197 | 197 |
TEMPLATE_DIGRAPH_TYPEDEFS(GR); |
198 | 198 |
|
199 | 199 |
typedef std::vector<int> IntVector; |
200 |
typedef std::vector<char> BoolVector; |
|
201 | 200 |
typedef std::vector<Value> ValueVector; |
202 | 201 |
typedef std::vector<Cost> CostVector; |
203 | 202 |
typedef std::vector<LargeCost> LargeCostVector; |
203 |
typedef std::vector<char> BoolVector; |
|
204 |
// Note: vector<char> is used instead of vector<bool> for efficiency reasons |
|
204 | 205 |
|
205 | 206 |
private: |
206 | 207 |
|
207 | 208 |
template <typename KT, typename VT> |
208 | 209 |
class StaticVectorMap { |
209 | 210 |
public: |
... | ... |
@@ -241,12 +242,13 @@ |
241 | 242 |
int _res_arc_num; |
242 | 243 |
int _root; |
243 | 244 |
|
244 | 245 |
// Parameters of the problem |
245 | 246 |
bool _have_lower; |
246 | 247 |
Value _sum_supply; |
248 |
int _sup_node_num; |
|
247 | 249 |
|
248 | 250 |
// Data structures for storing the digraph |
249 | 251 |
IntNodeMap _node_id; |
250 | 252 |
IntArcMap _arc_idf; |
251 | 253 |
IntArcMap _arc_idb; |
252 | 254 |
IntVector _first_out; |
... | ... |
@@ -269,12 +271,18 @@ |
269 | 271 |
std::deque<int> _active_nodes; |
270 | 272 |
|
271 | 273 |
// Data for scaling |
272 | 274 |
LargeCost _epsilon; |
273 | 275 |
int _alpha; |
274 | 276 |
|
277 |
IntVector _buckets; |
|
278 |
IntVector _bucket_next; |
|
279 |
IntVector _bucket_prev; |
|
280 |
IntVector _rank; |
|
281 |
int _max_rank; |
|
282 |
|
|
275 | 283 |
// Data for a StaticDigraph structure |
276 | 284 |
typedef std::pair<int, int> IntPair; |
277 | 285 |
StaticDigraph _sgr; |
278 | 286 |
std::vector<IntPair> _arc_vec; |
279 | 287 |
std::vector<LargeCost> _cost_vec; |
280 | 288 |
LargeCostArcMap _cost_map; |
... | ... |
@@ -799,12 +807,17 @@ |
799 | 807 |
} else { |
800 | 808 |
for (ArcIt a(_graph); a != INVALID; ++a) { |
801 | 809 |
cap[a] = _upper[_arc_idf[a]]; |
802 | 810 |
} |
803 | 811 |
} |
804 | 812 |
|
813 |
_sup_node_num = 0; |
|
814 |
for (NodeIt n(_graph); n != INVALID; ++n) { |
|
815 |
if (sup[n] > 0) ++_sup_node_num; |
|
816 |
} |
|
817 |
|
|
805 | 818 |
// Find a feasible flow using Circulation |
806 | 819 |
Circulation<Digraph, ConstMap<Arc, Value>, ValueArcMap, ValueNodeMap> |
807 | 820 |
circ(_graph, low, cap, sup); |
808 | 821 |
if (!circ.flowMap(flow).run()) return INFEASIBLE; |
809 | 822 |
|
810 | 823 |
// Set residual capacities and handle GEQ supply type |
... | ... |
@@ -833,13 +846,13 @@ |
833 | 846 |
Value fa = flow[a]; |
834 | 847 |
_res_cap[_arc_idf[a]] = cap[a] - fa; |
835 | 848 |
_res_cap[_arc_idb[a]] = fa; |
836 | 849 |
} |
837 | 850 |
for (int a = _first_out[_root]; a != _res_arc_num; ++a) { |
838 | 851 |
int ra = _reverse[a]; |
839 |
_res_cap[a] = |
|
852 |
_res_cap[a] = 0; |
|
840 | 853 |
_res_cap[ra] = 0; |
841 | 854 |
_cost[a] = 0; |
842 | 855 |
_cost[ra] = 0; |
843 | 856 |
} |
844 | 857 |
} |
845 | 858 |
|
... | ... |
@@ -847,13 +860,20 @@ |
847 | 860 |
} |
848 | 861 |
|
849 | 862 |
// Execute the algorithm and transform the results |
850 | 863 |
void start(Method method) { |
851 | 864 |
// Maximum path length for partial augment |
852 | 865 |
const int MAX_PATH_LENGTH = 4; |
853 |
|
|
866 |
|
|
867 |
// Initialize data structures for buckets |
|
868 |
_max_rank = _alpha * _res_node_num; |
|
869 |
_buckets.resize(_max_rank); |
|
870 |
_bucket_next.resize(_res_node_num + 1); |
|
871 |
_bucket_prev.resize(_res_node_num + 1); |
|
872 |
_rank.resize(_res_node_num + 1); |
|
873 |
|
|
854 | 874 |
// Execute the algorithm |
855 | 875 |
switch (method) { |
856 | 876 |
case PUSH: |
857 | 877 |
startPush(); |
858 | 878 |
break; |
859 | 879 |
case AUGMENT: |
... | ... |
@@ -886,237 +906,325 @@ |
886 | 906 |
int limit = _first_out[_root]; |
887 | 907 |
for (int j = 0; j != limit; ++j) { |
888 | 908 |
if (!_forward[j]) _res_cap[j] += _lower[j]; |
889 | 909 |
} |
890 | 910 |
} |
891 | 911 |
} |
912 |
|
|
913 |
// Initialize a cost scaling phase |
|
914 |
void initPhase() { |
|
915 |
// Saturate arcs not satisfying the optimality condition |
|
916 |
for (int u = 0; u != _res_node_num; ++u) { |
|
917 |
int last_out = _first_out[u+1]; |
|
918 |
LargeCost pi_u = _pi[u]; |
|
919 |
for (int a = _first_out[u]; a != last_out; ++a) { |
|
920 |
int v = _target[a]; |
|
921 |
if (_res_cap[a] > 0 && _cost[a] + pi_u - _pi[v] < 0) { |
|
922 |
Value delta = _res_cap[a]; |
|
923 |
_excess[u] -= delta; |
|
924 |
_excess[v] += delta; |
|
925 |
_res_cap[a] = 0; |
|
926 |
_res_cap[_reverse[a]] += delta; |
|
927 |
} |
|
928 |
} |
|
929 |
} |
|
930 |
|
|
931 |
// Find active nodes (i.e. nodes with positive excess) |
|
932 |
for (int u = 0; u != _res_node_num; ++u) { |
|
933 |
if (_excess[u] > 0) _active_nodes.push_back(u); |
|
934 |
} |
|
935 |
|
|
936 |
// Initialize the next arcs |
|
937 |
for (int u = 0; u != _res_node_num; ++u) { |
|
938 |
_next_out[u] = _first_out[u]; |
|
939 |
} |
|
940 |
} |
|
941 |
|
|
942 |
// Early termination heuristic |
|
943 |
bool earlyTermination() { |
|
944 |
const double EARLY_TERM_FACTOR = 3.0; |
|
945 |
|
|
946 |
// Build a static residual graph |
|
947 |
_arc_vec.clear(); |
|
948 |
_cost_vec.clear(); |
|
949 |
for (int j = 0; j != _res_arc_num; ++j) { |
|
950 |
if (_res_cap[j] > 0) { |
|
951 |
_arc_vec.push_back(IntPair(_source[j], _target[j])); |
|
952 |
_cost_vec.push_back(_cost[j] + 1); |
|
953 |
} |
|
954 |
} |
|
955 |
_sgr.build(_res_node_num, _arc_vec.begin(), _arc_vec.end()); |
|
956 |
|
|
957 |
// Run Bellman-Ford algorithm to check if the current flow is optimal |
|
958 |
BellmanFord<StaticDigraph, LargeCostArcMap> bf(_sgr, _cost_map); |
|
959 |
bf.init(0); |
|
960 |
bool done = false; |
|
961 |
int K = int(EARLY_TERM_FACTOR * std::sqrt(double(_res_node_num))); |
|
962 |
for (int i = 0; i < K && !done; ++i) { |
|
963 |
done = bf.processNextWeakRound(); |
|
964 |
} |
|
965 |
return done; |
|
966 |
} |
|
967 |
|
|
968 |
// Global potential update heuristic |
|
969 |
void globalUpdate() { |
|
970 |
int bucket_end = _root + 1; |
|
971 |
|
|
972 |
// Initialize buckets |
|
973 |
for (int r = 0; r != _max_rank; ++r) { |
|
974 |
_buckets[r] = bucket_end; |
|
975 |
} |
|
976 |
Value total_excess = 0; |
|
977 |
for (int i = 0; i != _res_node_num; ++i) { |
|
978 |
if (_excess[i] < 0) { |
|
979 |
_rank[i] = 0; |
|
980 |
_bucket_next[i] = _buckets[0]; |
|
981 |
_bucket_prev[_buckets[0]] = i; |
|
982 |
_buckets[0] = i; |
|
983 |
} else { |
|
984 |
total_excess += _excess[i]; |
|
985 |
_rank[i] = _max_rank; |
|
986 |
} |
|
987 |
} |
|
988 |
if (total_excess == 0) return; |
|
989 |
|
|
990 |
// Search the buckets |
|
991 |
int r = 0; |
|
992 |
for ( ; r != _max_rank; ++r) { |
|
993 |
while (_buckets[r] != bucket_end) { |
|
994 |
// Remove the first node from the current bucket |
|
995 |
int u = _buckets[r]; |
|
996 |
_buckets[r] = _bucket_next[u]; |
|
997 |
|
|
998 |
// Search the incomming arcs of u |
|
999 |
LargeCost pi_u = _pi[u]; |
|
1000 |
int last_out = _first_out[u+1]; |
|
1001 |
for (int a = _first_out[u]; a != last_out; ++a) { |
|
1002 |
int ra = _reverse[a]; |
|
1003 |
if (_res_cap[ra] > 0) { |
|
1004 |
int v = _source[ra]; |
|
1005 |
int old_rank_v = _rank[v]; |
|
1006 |
if (r < old_rank_v) { |
|
1007 |
// Compute the new rank of v |
|
1008 |
LargeCost nrc = (_cost[ra] + _pi[v] - pi_u) / _epsilon; |
|
1009 |
int new_rank_v = old_rank_v; |
|
1010 |
if (nrc < LargeCost(_max_rank)) |
|
1011 |
new_rank_v = r + 1 + int(nrc); |
|
1012 |
|
|
1013 |
// Change the rank of v |
|
1014 |
if (new_rank_v < old_rank_v) { |
|
1015 |
_rank[v] = new_rank_v; |
|
1016 |
_next_out[v] = _first_out[v]; |
|
1017 |
|
|
1018 |
// Remove v from its old bucket |
|
1019 |
if (old_rank_v < _max_rank) { |
|
1020 |
if (_buckets[old_rank_v] == v) { |
|
1021 |
_buckets[old_rank_v] = _bucket_next[v]; |
|
1022 |
} else { |
|
1023 |
_bucket_next[_bucket_prev[v]] = _bucket_next[v]; |
|
1024 |
_bucket_prev[_bucket_next[v]] = _bucket_prev[v]; |
|
1025 |
} |
|
1026 |
} |
|
1027 |
|
|
1028 |
// Insert v to its new bucket |
|
1029 |
_bucket_next[v] = _buckets[new_rank_v]; |
|
1030 |
_bucket_prev[_buckets[new_rank_v]] = v; |
|
1031 |
_buckets[new_rank_v] = v; |
|
1032 |
} |
|
1033 |
} |
|
1034 |
} |
|
1035 |
} |
|
1036 |
|
|
1037 |
// Finish search if there are no more active nodes |
|
1038 |
if (_excess[u] > 0) { |
|
1039 |
total_excess -= _excess[u]; |
|
1040 |
if (total_excess <= 0) break; |
|
1041 |
} |
|
1042 |
} |
|
1043 |
if (total_excess <= 0) break; |
|
1044 |
} |
|
1045 |
|
|
1046 |
// Relabel nodes |
|
1047 |
for (int u = 0; u != _res_node_num; ++u) { |
|
1048 |
int k = std::min(_rank[u], r); |
|
1049 |
if (k > 0) { |
|
1050 |
_pi[u] -= _epsilon * k; |
|
1051 |
_next_out[u] = _first_out[u]; |
|
1052 |
} |
|
1053 |
} |
|
1054 |
} |
|
892 | 1055 |
|
893 | 1056 |
/// Execute the algorithm performing augment and relabel operations |
894 | 1057 |
void startAugment(int max_length = std::numeric_limits<int>::max()) { |
895 | 1058 |
// Paramters for heuristics |
896 |
const int BF_HEURISTIC_EPSILON_BOUND = 1000; |
|
897 |
const int BF_HEURISTIC_BOUND_FACTOR = 3; |
|
1059 |
const int EARLY_TERM_EPSILON_LIMIT = 1000; |
|
1060 |
const double GLOBAL_UPDATE_FACTOR = 3.0; |
|
898 | 1061 |
|
1062 |
const int global_update_freq = int(GLOBAL_UPDATE_FACTOR * |
|
1063 |
(_res_node_num + _sup_node_num * _sup_node_num)); |
|
1064 |
int next_update_limit = global_update_freq; |
|
1065 |
|
|
1066 |
int relabel_cnt = 0; |
|
1067 |
|
|
899 | 1068 |
// Perform cost scaling phases |
900 |
IntVector pred_arc(_res_node_num); |
|
901 |
std::vector<int> path_nodes; |
|
1069 |
std::vector<int> path; |
|
902 | 1070 |
for ( ; _epsilon >= 1; _epsilon = _epsilon < _alpha && _epsilon > 1 ? |
903 | 1071 |
1 : _epsilon / _alpha ) |
904 | 1072 |
{ |
905 |
// "Early Termination" heuristic: use Bellman-Ford algorithm |
|
906 |
// to check if the current flow is optimal |
|
907 |
if (_epsilon <= BF_HEURISTIC_EPSILON_BOUND) { |
|
908 |
_arc_vec.clear(); |
|
909 |
_cost_vec.clear(); |
|
910 |
for (int j = 0; j != _res_arc_num; ++j) { |
|
911 |
if (_res_cap[j] > 0) { |
|
912 |
_arc_vec.push_back(IntPair(_source[j], _target[j])); |
|
913 |
_cost_vec.push_back(_cost[j] + 1); |
|
914 |
} |
|
915 |
} |
|
916 |
_sgr.build(_res_node_num, _arc_vec.begin(), _arc_vec.end()); |
|
917 |
|
|
918 |
BellmanFord<StaticDigraph, LargeCostArcMap> bf(_sgr, _cost_map); |
|
919 |
bf.init(0); |
|
920 |
bool done = false; |
|
921 |
int K = int(BF_HEURISTIC_BOUND_FACTOR * sqrt(_res_node_num)); |
|
922 |
for (int i = 0; i < K && !done; ++i) |
|
923 |
done = bf.processNextWeakRound(); |
|
924 |
if (done) break; |
|
925 |
} |
|
926 |
|
|
927 |
// Saturate arcs not satisfying the optimality condition |
|
928 |
for (int a = 0; a != _res_arc_num; ++a) { |
|
929 |
if (_res_cap[a] > 0 && |
|
930 |
_cost[a] + _pi[_source[a]] - _pi[_target[a]] < 0) { |
|
931 |
Value delta = _res_cap[a]; |
|
932 |
_excess[_source[a]] -= delta; |
|
933 |
_excess[_target[a]] += delta; |
|
934 |
_res_cap[a] = 0; |
|
935 |
_res_cap[_reverse[a]] += delta; |
|
936 |
} |
|
1073 |
// Early termination heuristic |
|
1074 |
if (_epsilon <= EARLY_TERM_EPSILON_LIMIT) { |
|
1075 |
if (earlyTermination()) break; |
|
937 | 1076 |
} |
938 | 1077 |
|
939 |
// Find active nodes (i.e. nodes with positive excess) |
|
940 |
for (int u = 0; u != _res_node_num; ++u) { |
|
941 |
if (_excess[u] > 0) _active_nodes.push_back(u); |
|
942 |
} |
|
943 |
|
|
944 |
// Initialize the next arcs |
|
945 |
for (int u = 0; u != _res_node_num; ++u) { |
|
946 |
_next_out[u] = _first_out[u]; |
|
947 |
} |
|
948 |
|
|
1078 |
// Initialize current phase |
|
1079 |
initPhase(); |
|
1080 |
|
|
949 | 1081 |
// Perform partial augment and relabel operations |
950 | 1082 |
while (true) { |
951 | 1083 |
// Select an active node (FIFO selection) |
952 | 1084 |
while (_active_nodes.size() > 0 && |
953 | 1085 |
_excess[_active_nodes.front()] <= 0) { |
954 | 1086 |
_active_nodes.pop_front(); |
955 | 1087 |
} |
956 | 1088 |
if (_active_nodes.size() == 0) break; |
957 | 1089 |
int start = _active_nodes.front(); |
958 |
path_nodes.clear(); |
|
959 |
path_nodes.push_back(start); |
|
960 | 1090 |
|
961 | 1091 |
// Find an augmenting path from the start node |
1092 |
path.clear(); |
|
962 | 1093 |
int tip = start; |
963 |
while (_excess[tip] >= 0 && |
|
964 |
int(path_nodes.size()) <= max_length) { |
|
1094 |
while (_excess[tip] >= 0 && int(path.size()) < max_length) { |
|
965 | 1095 |
int u; |
966 |
LargeCost min_red_cost, rc; |
|
967 |
int last_out = _sum_supply < 0 ? |
|
968 |
|
|
1096 |
LargeCost min_red_cost, rc, pi_tip = _pi[tip]; |
|
1097 |
int last_out = _first_out[tip+1]; |
|
969 | 1098 |
for (int a = _next_out[tip]; a != last_out; ++a) { |
970 |
if (_res_cap[a] > 0 && |
|
971 |
_cost[a] + _pi[_source[a]] - _pi[_target[a]] < 0) { |
|
972 |
u = _target[a]; |
|
973 |
pred_arc[u] = a; |
|
1099 |
u = _target[a]; |
|
1100 |
if (_res_cap[a] > 0 && _cost[a] + pi_tip - _pi[u] < 0) { |
|
1101 |
path.push_back(a); |
|
974 | 1102 |
_next_out[tip] = a; |
975 | 1103 |
tip = u; |
976 |
path_nodes.push_back(tip); |
|
977 | 1104 |
goto next_step; |
978 | 1105 |
} |
979 | 1106 |
} |
980 | 1107 |
|
981 | 1108 |
// Relabel tip node |
982 |
min_red_cost = std::numeric_limits<LargeCost>::max() |
|
1109 |
min_red_cost = std::numeric_limits<LargeCost>::max(); |
|
1110 |
if (tip != start) { |
|
1111 |
int ra = _reverse[path.back()]; |
|
1112 |
min_red_cost = _cost[ra] + pi_tip - _pi[_target[ra]]; |
|
1113 |
} |
|
983 | 1114 |
for (int a = _first_out[tip]; a != last_out; ++a) { |
984 |
rc = _cost[a] + |
|
1115 |
rc = _cost[a] + pi_tip - _pi[_target[a]]; |
|
985 | 1116 |
if (_res_cap[a] > 0 && rc < min_red_cost) { |
986 | 1117 |
min_red_cost = rc; |
987 | 1118 |
} |
988 | 1119 |
} |
989 | 1120 |
_pi[tip] -= min_red_cost + _epsilon; |
990 |
|
|
991 |
// Reset the next arc of tip |
|
992 | 1121 |
_next_out[tip] = _first_out[tip]; |
1122 |
++relabel_cnt; |
|
993 | 1123 |
|
994 | 1124 |
// Step back |
995 | 1125 |
if (tip != start) { |
996 |
path_nodes.pop_back(); |
|
997 |
tip = path_nodes.back(); |
|
1126 |
tip = _source[path.back()]; |
|
1127 |
path.pop_back(); |
|
998 | 1128 |
} |
999 | 1129 |
|
1000 | 1130 |
next_step: ; |
1001 | 1131 |
} |
1002 | 1132 |
|
1003 | 1133 |
// Augment along the found path (as much flow as possible) |
1004 | 1134 |
Value delta; |
1005 |
int u, v = path_nodes.front(), pa; |
|
1006 |
for (int i = 1; i < int(path_nodes.size()); ++i) { |
|
1135 |
int pa, u, v = start; |
|
1136 |
for (int i = 0; i != int(path.size()); ++i) { |
|
1137 |
pa = path[i]; |
|
1007 | 1138 |
u = v; |
1008 |
v = path_nodes[i]; |
|
1009 |
pa = pred_arc[v]; |
|
1139 |
v = _target[pa]; |
|
1010 | 1140 |
delta = std::min(_res_cap[pa], _excess[u]); |
1011 | 1141 |
_res_cap[pa] -= delta; |
1012 | 1142 |
_res_cap[_reverse[pa]] += delta; |
1013 | 1143 |
_excess[u] -= delta; |
1014 | 1144 |
_excess[v] += delta; |
1015 | 1145 |
if (_excess[v] > 0 && _excess[v] <= delta) |
1016 | 1146 |
_active_nodes.push_back(v); |
1017 | 1147 |
} |
1148 |
|
|
1149 |
// Global update heuristic |
|
1150 |
if (relabel_cnt >= next_update_limit) { |
|
1151 |
globalUpdate(); |
|
1152 |
next_update_limit += global_update_freq; |
|
1153 |
} |
|
1018 | 1154 |
} |
1019 | 1155 |
} |
1020 | 1156 |
} |
1021 | 1157 |
|
1022 | 1158 |
/// Execute the algorithm performing push and relabel operations |
1023 | 1159 |
void startPush() { |
1024 | 1160 |
// Paramters for heuristics |
1025 |
const int BF_HEURISTIC_EPSILON_BOUND = 1000; |
|
1026 |
const int BF_HEURISTIC_BOUND_FACTOR = 3; |
|
1161 |
const int EARLY_TERM_EPSILON_LIMIT = 1000; |
|
1162 |
const double GLOBAL_UPDATE_FACTOR = 2.0; |
|
1027 | 1163 |
|
1164 |
const int global_update_freq = int(GLOBAL_UPDATE_FACTOR * |
|
1165 |
(_res_node_num + _sup_node_num * _sup_node_num)); |
|
1166 |
int next_update_limit = global_update_freq; |
|
1167 |
|
|
1168 |
int relabel_cnt = 0; |
|
1169 |
|
|
1028 | 1170 |
// Perform cost scaling phases |
1029 | 1171 |
BoolVector hyper(_res_node_num, false); |
1172 |
LargeCostVector hyper_cost(_res_node_num); |
|
1030 | 1173 |
for ( ; _epsilon >= 1; _epsilon = _epsilon < _alpha && _epsilon > 1 ? |
1031 | 1174 |
1 : _epsilon / _alpha ) |
1032 | 1175 |
{ |
1033 |
// "Early Termination" heuristic: use Bellman-Ford algorithm |
|
1034 |
// to check if the current flow is optimal |
|
1035 |
if (_epsilon <= BF_HEURISTIC_EPSILON_BOUND) { |
|
1036 |
_arc_vec.clear(); |
|
1037 |
_cost_vec.clear(); |
|
1038 |
for (int j = 0; j != _res_arc_num; ++j) { |
|
1039 |
if (_res_cap[j] > 0) { |
|
1040 |
_arc_vec.push_back(IntPair(_source[j], _target[j])); |
|
1041 |
_cost_vec.push_back(_cost[j] + 1); |
|
1042 |
} |
|
1043 |
} |
|
1044 |
_sgr.build(_res_node_num, _arc_vec.begin(), _arc_vec.end()); |
|
1045 |
|
|
1046 |
BellmanFord<StaticDigraph, LargeCostArcMap> bf(_sgr, _cost_map); |
|
1047 |
bf.init(0); |
|
1048 |
bool done = false; |
|
1049 |
int K = int(BF_HEURISTIC_BOUND_FACTOR * sqrt(_res_node_num)); |
|
1050 |
for (int i = 0; i < K && !done; ++i) |
|
1051 |
done = bf.processNextWeakRound(); |
|
1052 |
if (done) break; |
|
1176 |
// Early termination heuristic |
|
1177 |
if (_epsilon <= EARLY_TERM_EPSILON_LIMIT) { |
|
1178 |
if (earlyTermination()) break; |
|
1053 | 1179 |
} |
1054 |
|
|
1055 |
// Saturate arcs not satisfying the optimality condition |
|
1056 |
for (int a = 0; a != _res_arc_num; ++a) { |
|
1057 |
if (_res_cap[a] > 0 && |
|
1058 |
_cost[a] + _pi[_source[a]] - _pi[_target[a]] < 0) { |
|
1059 |
Value delta = _res_cap[a]; |
|
1060 |
_excess[_source[a]] -= delta; |
|
1061 |
_excess[_target[a]] += delta; |
|
1062 |
_res_cap[a] = 0; |
|
1063 |
_res_cap[_reverse[a]] += delta; |
|
1064 |
} |
|
1065 |
} |
|
1066 |
|
|
1067 |
// Find active nodes (i.e. nodes with positive excess) |
|
1068 |
for (int u = 0; u != _res_node_num; ++u) { |
|
1069 |
if (_excess[u] > 0) _active_nodes.push_back(u); |
|
1070 |
} |
|
1071 |
|
|
1072 |
// Initialize the next arcs |
|
1073 |
for (int u = 0; u != _res_node_num; ++u) { |
|
1074 |
_next_out[u] = _first_out[u]; |
|
1075 |
} |
|
1180 |
|
|
1181 |
// Initialize current phase |
|
1182 |
initPhase(); |
|
1076 | 1183 |
|
1077 | 1184 |
// Perform push and relabel operations |
1078 | 1185 |
while (_active_nodes.size() > 0) { |
1079 |
LargeCost min_red_cost, rc; |
|
1186 |
LargeCost min_red_cost, rc, pi_n; |
|
1080 | 1187 |
Value delta; |
1081 | 1188 |
int n, t, a, last_out = _res_arc_num; |
1082 | 1189 |
|
1190 |
next_node: |
|
1083 | 1191 |
// Select an active node (FIFO selection) |
1084 |
next_node: |
|
1085 | 1192 |
n = _active_nodes.front(); |
1086 |
last_out = _sum_supply < 0 ? |
|
1087 |
_first_out[n+1] : _first_out[n+1] - 1; |
|
1088 |
|
|
1193 |
last_out = _first_out[n+1]; |
|
1194 |
pi_n = _pi[n]; |
|
1195 |
|
|
1089 | 1196 |
// Perform push operations if there are admissible arcs |
1090 | 1197 |
if (_excess[n] > 0) { |
1091 | 1198 |
for (a = _next_out[n]; a != last_out; ++a) { |
1092 | 1199 |
if (_res_cap[a] > 0 && |
1093 |
_cost[a] + |
|
1200 |
_cost[a] + pi_n - _pi[_target[a]] < 0) { |
|
1094 | 1201 |
delta = std::min(_res_cap[a], _excess[n]); |
1095 | 1202 |
t = _target[a]; |
1096 | 1203 |
|
1097 | 1204 |
// Push-look-ahead heuristic |
1098 | 1205 |
Value ahead = -_excess[t]; |
1099 |
int last_out_t = _sum_supply < 0 ? |
|
1100 |
_first_out[t+1] : _first_out[t+1] - 1; |
|
1206 |
int last_out_t = _first_out[t+1]; |
|
1207 |
LargeCost pi_t = _pi[t]; |
|
1101 | 1208 |
for (int ta = _next_out[t]; ta != last_out_t; ++ta) { |
1102 | 1209 |
if (_res_cap[ta] > 0 && |
1103 |
_cost[ta] + |
|
1210 |
_cost[ta] + pi_t - _pi[_target[ta]] < 0) |
|
1104 | 1211 |
ahead += _res_cap[ta]; |
1105 | 1212 |
if (ahead >= delta) break; |
1106 | 1213 |
} |
1107 | 1214 |
if (ahead < 0) ahead = 0; |
1108 | 1215 |
|
1109 | 1216 |
// Push flow along the arc |
1110 |
if (ahead < delta) { |
|
1217 |
if (ahead < delta && !hyper[t]) { |
|
1111 | 1218 |
_res_cap[a] -= ahead; |
1112 | 1219 |
_res_cap[_reverse[a]] += ahead; |
1113 | 1220 |
_excess[n] -= ahead; |
1114 | 1221 |
_excess[t] += ahead; |
1115 | 1222 |
_active_nodes.push_front(t); |
1116 | 1223 |
hyper[t] = true; |
1224 |
hyper_cost[t] = _cost[a] + pi_n - pi_t; |
|
1117 | 1225 |
_next_out[n] = a; |
1118 | 1226 |
goto next_node; |
1119 | 1227 |
} else { |
1120 | 1228 |
_res_cap[a] -= delta; |
1121 | 1229 |
_res_cap[_reverse[a]] += delta; |
1122 | 1230 |
_excess[n] -= delta; |
... | ... |
@@ -1133,33 +1241,41 @@ |
1133 | 1241 |
} |
1134 | 1242 |
_next_out[n] = a; |
1135 | 1243 |
} |
1136 | 1244 |
|
1137 | 1245 |
// Relabel the node if it is still active (or hyper) |
1138 | 1246 |
if (_excess[n] > 0 || hyper[n]) { |
1139 |
min_red_cost = |
|
1247 |
min_red_cost = hyper[n] ? -hyper_cost[n] : |
|
1248 |
std::numeric_limits<LargeCost>::max(); |
|
1140 | 1249 |
for (int a = _first_out[n]; a != last_out; ++a) { |
1141 |
rc = _cost[a] + |
|
1250 |
rc = _cost[a] + pi_n - _pi[_target[a]]; |
|
1142 | 1251 |
if (_res_cap[a] > 0 && rc < min_red_cost) { |
1143 | 1252 |
min_red_cost = rc; |
1144 | 1253 |
} |
1145 | 1254 |
} |
1146 | 1255 |
_pi[n] -= min_red_cost + _epsilon; |
1256 |
_next_out[n] = _first_out[n]; |
|
1147 | 1257 |
hyper[n] = false; |
1148 |
|
|
1149 |
// Reset the next arc |
|
1150 |
|
|
1258 |
++relabel_cnt; |
|
1151 | 1259 |
} |
1152 | 1260 |
|
1153 | 1261 |
// Remove nodes that are not active nor hyper |
1154 | 1262 |
remove_nodes: |
1155 | 1263 |
while ( _active_nodes.size() > 0 && |
1156 | 1264 |
_excess[_active_nodes.front()] <= 0 && |
1157 | 1265 |
!hyper[_active_nodes.front()] ) { |
1158 | 1266 |
_active_nodes.pop_front(); |
1159 | 1267 |
} |
1268 |
|
|
1269 |
// Global update heuristic |
|
1270 |
if (relabel_cnt >= next_update_limit) { |
|
1271 |
globalUpdate(); |
|
1272 |
for (int u = 0; u != _res_node_num; ++u) |
|
1273 |
hyper[u] = false; |
|
1274 |
next_update_limit += global_update_freq; |
|
1275 |
} |
|
1160 | 1276 |
} |
1161 | 1277 |
} |
1162 | 1278 |
} |
1163 | 1279 |
|
1164 | 1280 |
}; //class CostScaling |
1165 | 1281 |
... | ... |
@@ -141,16 +141,17 @@ |
141 | 141 |
|
142 | 142 |
private: |
143 | 143 |
|
144 | 144 |
TEMPLATE_DIGRAPH_TYPEDEFS(GR); |
145 | 145 |
|
146 | 146 |
typedef std::vector<int> IntVector; |
147 |
typedef std::vector<char> CharVector; |
|
148 | 147 |
typedef std::vector<double> DoubleVector; |
149 | 148 |
typedef std::vector<Value> ValueVector; |
150 | 149 |
typedef std::vector<Cost> CostVector; |
150 |
typedef std::vector<char> BoolVector; |
|
151 |
// Note: vector<char> is used instead of vector<bool> for efficiency reasons |
|
151 | 152 |
|
152 | 153 |
private: |
153 | 154 |
|
154 | 155 |
template <typename KT, typename VT> |
155 | 156 |
class StaticVectorMap { |
156 | 157 |
public: |
... | ... |
@@ -195,13 +196,13 @@ |
195 | 196 |
|
196 | 197 |
// Data structures for storing the digraph |
197 | 198 |
IntNodeMap _node_id; |
198 | 199 |
IntArcMap _arc_idf; |
199 | 200 |
IntArcMap _arc_idb; |
200 | 201 |
IntVector _first_out; |
201 |
|
|
202 |
BoolVector _forward; |
|
202 | 203 |
IntVector _source; |
203 | 204 |
IntVector _target; |
204 | 205 |
IntVector _reverse; |
205 | 206 |
|
206 | 207 |
// Node and arc data |
207 | 208 |
ValueVector _lower; |
... | ... |
@@ -930,14 +931,14 @@ |
930 | 931 |
const double LIMIT_FACTOR = 1.0; |
931 | 932 |
const int MIN_LIMIT = 5; |
932 | 933 |
|
933 | 934 |
// Contruct auxiliary data vectors |
934 | 935 |
DoubleVector pi(_res_node_num, 0.0); |
935 | 936 |
IntVector level(_res_node_num); |
936 |
CharVector reached(_res_node_num); |
|
937 |
CharVector processed(_res_node_num); |
|
937 |
BoolVector reached(_res_node_num); |
|
938 |
BoolVector processed(_res_node_num); |
|
938 | 939 |
IntVector pred_node(_res_node_num); |
939 | 940 |
IntVector pred_arc(_res_node_num); |
940 | 941 |
std::vector<int> stack(_res_node_num); |
941 | 942 |
std::vector<int> proc_vector(_res_node_num); |
942 | 943 |
|
943 | 944 |
// Initialize epsilon |
... | ... |
@@ -161,15 +161,16 @@ |
161 | 161 |
|
162 | 162 |
private: |
163 | 163 |
|
164 | 164 |
TEMPLATE_DIGRAPH_TYPEDEFS(GR); |
165 | 165 |
|
166 | 166 |
typedef std::vector<int> IntVector; |
167 |
typedef std::vector<char> CharVector; |
|
168 | 167 |
typedef std::vector<Value> ValueVector; |
169 | 168 |
typedef std::vector<Cost> CostVector; |
169 |
typedef std::vector<char> BoolVector; |
|
170 |
// Note: vector<char> is used instead of vector<bool> for efficiency reasons |
|
170 | 171 |
|
171 | 172 |
// State constants for arcs |
172 | 173 |
enum ArcStateEnum { |
173 | 174 |
STATE_UPPER = -1, |
174 | 175 |
STATE_TREE = 0, |
175 | 176 |
STATE_LOWER = 1 |
... | ... |
@@ -209,14 +210,14 @@ |
209 | 210 |
IntVector _pred; |
210 | 211 |
IntVector _thread; |
211 | 212 |
IntVector _rev_thread; |
212 | 213 |
IntVector _succ_num; |
213 | 214 |
IntVector _last_succ; |
214 | 215 |
IntVector _dirty_revs; |
215 |
CharVector _forward; |
|
216 |
CharVector _state; |
|
216 |
BoolVector _forward; |
|
217 |
BoolVector _state; |
|
217 | 218 |
int _root; |
218 | 219 |
|
219 | 220 |
// Temporary data used in the current pivot iteration |
220 | 221 |
int in_arc, join, u_in, v_in, u_out, v_out; |
221 | 222 |
int first, second, right, last; |
222 | 223 |
int stem, par_stem, new_stem; |
... | ... |
@@ -241,13 +242,13 @@ |
241 | 242 |
private: |
242 | 243 |
|
243 | 244 |
// References to the NetworkSimplex class |
244 | 245 |
const IntVector &_source; |
245 | 246 |
const IntVector &_target; |
246 | 247 |
const CostVector &_cost; |
247 |
const |
|
248 |
const BoolVector &_state; |
|
248 | 249 |
const CostVector &_pi; |
249 | 250 |
int &_in_arc; |
250 | 251 |
int _search_arc_num; |
251 | 252 |
|
252 | 253 |
// Pivot rule data |
253 | 254 |
int _next_arc; |
... | ... |
@@ -262,21 +263,21 @@ |
262 | 263 |
_next_arc(0) |
263 | 264 |
{} |
264 | 265 |
|
265 | 266 |
// Find next entering arc |
266 | 267 |
bool findEnteringArc() { |
267 | 268 |
Cost c; |
268 |
for (int e = _next_arc; e |
|
269 |
for (int e = _next_arc; e != _search_arc_num; ++e) { |
|
269 | 270 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
270 | 271 |
if (c < 0) { |
271 | 272 |
_in_arc = e; |
272 | 273 |
_next_arc = e + 1; |
273 | 274 |
return true; |
274 | 275 |
} |
275 | 276 |
} |
276 |
for (int e = 0; e |
|
277 |
for (int e = 0; e != _next_arc; ++e) { |
|
277 | 278 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
278 | 279 |
if (c < 0) { |
279 | 280 |
_in_arc = e; |
280 | 281 |
_next_arc = e + 1; |
281 | 282 |
return true; |
282 | 283 |
} |
... | ... |
@@ -293,13 +294,13 @@ |
293 | 294 |
private: |
294 | 295 |
|
295 | 296 |
// References to the NetworkSimplex class |
296 | 297 |
const IntVector &_source; |
297 | 298 |
const IntVector &_target; |
298 | 299 |
const CostVector &_cost; |
299 |
const |
|
300 |
const BoolVector &_state; |
|
300 | 301 |
const CostVector &_pi; |
301 | 302 |
int &_in_arc; |
302 | 303 |
int _search_arc_num; |
303 | 304 |
|
304 | 305 |
public: |
305 | 306 |
|
... | ... |
@@ -310,13 +311,13 @@ |
310 | 311 |
_in_arc(ns.in_arc), _search_arc_num(ns._search_arc_num) |
311 | 312 |
{} |
312 | 313 |
|
313 | 314 |
// Find next entering arc |
314 | 315 |
bool findEnteringArc() { |
315 | 316 |
Cost c, min = 0; |
316 |
for (int e = 0; e |
|
317 |
for (int e = 0; e != _search_arc_num; ++e) { |
|
317 | 318 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
318 | 319 |
if (c < min) { |
319 | 320 |
min = c; |
320 | 321 |
_in_arc = e; |
321 | 322 |
} |
322 | 323 |
} |
... | ... |
@@ -332,13 +333,13 @@ |
332 | 333 |
private: |
333 | 334 |
|
334 | 335 |
// References to the NetworkSimplex class |
335 | 336 |
const IntVector &_source; |
336 | 337 |
const IntVector &_target; |
337 | 338 |
const CostVector &_cost; |
338 |
const |
|
339 |
const BoolVector &_state; |
|
339 | 340 |
const CostVector &_pi; |
340 | 341 |
int &_in_arc; |
341 | 342 |
int _search_arc_num; |
342 | 343 |
|
343 | 344 |
// Pivot rule data |
344 | 345 |
int _block_size; |
... | ... |
@@ -351,37 +352,37 @@ |
351 | 352 |
_source(ns._source), _target(ns._target), |
352 | 353 |
_cost(ns._cost), _state(ns._state), _pi(ns._pi), |
353 | 354 |
_in_arc(ns.in_arc), _search_arc_num(ns._search_arc_num), |
354 | 355 |
_next_arc(0) |
355 | 356 |
{ |
356 | 357 |
// The main parameters of the pivot rule |
357 |
const double BLOCK_SIZE_FACTOR = |
|
358 |
const double BLOCK_SIZE_FACTOR = 1.0; |
|
358 | 359 |
const int MIN_BLOCK_SIZE = 10; |
359 | 360 |
|
360 | 361 |
_block_size = std::max( int(BLOCK_SIZE_FACTOR * |
361 | 362 |
std::sqrt(double(_search_arc_num))), |
362 | 363 |
MIN_BLOCK_SIZE ); |
363 | 364 |
} |
364 | 365 |
|
365 | 366 |
// Find next entering arc |
366 | 367 |
bool findEnteringArc() { |
367 | 368 |
Cost c, min = 0; |
368 | 369 |
int cnt = _block_size; |
369 | 370 |
int e; |
370 |
for (e = _next_arc; e |
|
371 |
for (e = _next_arc; e != _search_arc_num; ++e) { |
|
371 | 372 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
372 | 373 |
if (c < min) { |
373 | 374 |
min = c; |
374 | 375 |
_in_arc = e; |
375 | 376 |
} |
376 | 377 |
if (--cnt == 0) { |
377 | 378 |
if (min < 0) goto search_end; |
378 | 379 |
cnt = _block_size; |
379 | 380 |
} |
380 | 381 |
} |
381 |
for (e = 0; e |
|
382 |
for (e = 0; e != _next_arc; ++e) { |
|
382 | 383 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
383 | 384 |
if (c < min) { |
384 | 385 |
min = c; |
385 | 386 |
_in_arc = e; |
386 | 387 |
} |
387 | 388 |
if (--cnt == 0) { |
... | ... |
@@ -405,13 +406,13 @@ |
405 | 406 |
private: |
406 | 407 |
|
407 | 408 |
// References to the NetworkSimplex class |
408 | 409 |
const IntVector &_source; |
409 | 410 |
const IntVector &_target; |
410 | 411 |
const CostVector &_cost; |
411 |
const |
|
412 |
const BoolVector &_state; |
|
412 | 413 |
const CostVector &_pi; |
413 | 414 |
int &_in_arc; |
414 | 415 |
int _search_arc_num; |
415 | 416 |
|
416 | 417 |
// Pivot rule data |
417 | 418 |
IntVector _candidates; |
... | ... |
@@ -466,24 +467,24 @@ |
466 | 467 |
if (min < 0) return true; |
467 | 468 |
} |
468 | 469 |
|
469 | 470 |
// Major iteration: build a new candidate list |
470 | 471 |
min = 0; |
471 | 472 |
_curr_length = 0; |
472 |
for (e = _next_arc; e |
|
473 |
for (e = _next_arc; e != _search_arc_num; ++e) { |
|
473 | 474 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
474 | 475 |
if (c < 0) { |
475 | 476 |
_candidates[_curr_length++] = e; |
476 | 477 |
if (c < min) { |
477 | 478 |
min = c; |
478 | 479 |
_in_arc = e; |
479 | 480 |
} |
480 | 481 |
if (_curr_length == _list_length) goto search_end; |
481 | 482 |
} |
482 | 483 |
} |
483 |
for (e = 0; e |
|
484 |
for (e = 0; e != _next_arc; ++e) { |
|
484 | 485 |
c = _state[e] * (_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
485 | 486 |
if (c < 0) { |
486 | 487 |
_candidates[_curr_length++] = e; |
487 | 488 |
if (c < min) { |
488 | 489 |
min = c; |
489 | 490 |
_in_arc = e; |
... | ... |
@@ -508,13 +509,13 @@ |
508 | 509 |
private: |
509 | 510 |
|
510 | 511 |
// References to the NetworkSimplex class |
511 | 512 |
const IntVector &_source; |
512 | 513 |
const IntVector &_target; |
513 | 514 |
const CostVector &_cost; |
514 |
const |
|
515 |
const BoolVector &_state; |
|
515 | 516 |
const CostVector &_pi; |
516 | 517 |
int &_in_arc; |
517 | 518 |
int _search_arc_num; |
518 | 519 |
|
519 | 520 |
// Pivot rule data |
520 | 521 |
int _block_size, _head_length, _curr_length; |
... | ... |
@@ -561,38 +562,38 @@ |
561 | 562 |
} |
562 | 563 |
|
563 | 564 |
// Find next entering arc |
564 | 565 |
bool findEnteringArc() { |
565 | 566 |
// Check the current candidate list |
566 | 567 |
int e; |
567 |
for (int i = 0; i |
|
568 |
for (int i = 0; i != _curr_length; ++i) { |
|
568 | 569 |
e = _candidates[i]; |
569 | 570 |
_cand_cost[e] = _state[e] * |
570 | 571 |
(_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
571 | 572 |
if (_cand_cost[e] >= 0) { |
572 | 573 |
_candidates[i--] = _candidates[--_curr_length]; |
573 | 574 |
} |
574 | 575 |
} |
575 | 576 |
|
576 | 577 |
// Extend the list |
577 | 578 |
int cnt = _block_size; |
578 | 579 |
int limit = _head_length; |
579 | 580 |
|
580 |
for (e = _next_arc; e |
|
581 |
for (e = _next_arc; e != _search_arc_num; ++e) { |
|
581 | 582 |
_cand_cost[e] = _state[e] * |
582 | 583 |
(_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
583 | 584 |
if (_cand_cost[e] < 0) { |
584 | 585 |
_candidates[_curr_length++] = e; |
585 | 586 |
} |
586 | 587 |
if (--cnt == 0) { |
587 | 588 |
if (_curr_length > limit) goto search_end; |
588 | 589 |
limit = 0; |
589 | 590 |
cnt = _block_size; |
590 | 591 |
} |
591 | 592 |
} |
592 |
for (e = 0; e |
|
593 |
for (e = 0; e != _next_arc; ++e) { |
|
593 | 594 |
_cand_cost[e] = _state[e] * |
594 | 595 |
(_cost[e] + _pi[_source[e]] - _pi[_target[e]]); |
595 | 596 |
if (_cand_cost[e] < 0) { |
596 | 597 |
_candidates[_curr_length++] = e; |
597 | 598 |
} |
598 | 599 |
if (--cnt == 0) { |
... | ... |
@@ -1325,13 +1326,13 @@ |
1325 | 1326 |
if (old_rev_thread != v_in) { |
1326 | 1327 |
_thread[old_rev_thread] = right; |
1327 | 1328 |
_rev_thread[right] = old_rev_thread; |
1328 | 1329 |
} |
1329 | 1330 |
|
1330 | 1331 |
// Update _rev_thread using the new _thread values |
1331 |
for (int i = 0; i |
|
1332 |
for (int i = 0; i != int(_dirty_revs.size()); ++i) { |
|
1332 | 1333 |
u = _dirty_revs[i]; |
1333 | 1334 |
_rev_thread[_thread[u]] = u; |
1334 | 1335 |
} |
1335 | 1336 |
|
1336 | 1337 |
// Update _pred, _forward, _last_succ and _succ_num for the |
1337 | 1338 |
// stem nodes from u_out to u_in |
... | ... |
@@ -1397,12 +1398,106 @@ |
1397 | 1398 |
int end = _thread[_last_succ[u_in]]; |
1398 | 1399 |
for (int u = u_in; u != end; u = _thread[u]) { |
1399 | 1400 |
_pi[u] += sigma; |
1400 | 1401 |
} |
1401 | 1402 |
} |
1402 | 1403 |
|
1404 |
// Heuristic initial pivots |
|
1405 |
bool initialPivots() { |
|
1406 |
Value curr, total = 0; |
|
1407 |
std::vector<Node> supply_nodes, demand_nodes; |
|
1408 |
for (NodeIt u(_graph); u != INVALID; ++u) { |
|
1409 |
curr = _supply[_node_id[u]]; |
|
1410 |
if (curr > 0) { |
|
1411 |
total += curr; |
|
1412 |
supply_nodes.push_back(u); |
|
1413 |
} |
|
1414 |
else if (curr < 0) { |
|
1415 |
demand_nodes.push_back(u); |
|
1416 |
} |
|
1417 |
} |
|
1418 |
if (_sum_supply > 0) total -= _sum_supply; |
|
1419 |
if (total <= 0) return true; |
|
1420 |
|
|
1421 |
IntVector arc_vector; |
|
1422 |
if (_sum_supply >= 0) { |
|
1423 |
if (supply_nodes.size() == 1 && demand_nodes.size() == 1) { |
|
1424 |
// Perform a reverse graph search from the sink to the source |
|
1425 |
typename GR::template NodeMap<bool> reached(_graph, false); |
|
1426 |
Node s = supply_nodes[0], t = demand_nodes[0]; |
|
1427 |
std::vector<Node> stack; |
|
1428 |
reached[t] = true; |
|
1429 |
stack.push_back(t); |
|
1430 |
while (!stack.empty()) { |
|
1431 |
Node u, v = stack.back(); |
|
1432 |
stack.pop_back(); |
|
1433 |
if (v == s) break; |
|
1434 |
for (InArcIt a(_graph, v); a != INVALID; ++a) { |
|
1435 |
if (reached[u = _graph.source(a)]) continue; |
|
1436 |
int j = _arc_id[a]; |
|
1437 |
if (_cap[j] >= total) { |
|
1438 |
arc_vector.push_back(j); |
|
1439 |
reached[u] = true; |
|
1440 |
stack.push_back(u); |
|
1441 |
} |
|
1442 |
} |
|
1443 |
} |
|
1444 |
} else { |
|
1445 |
// Find the min. cost incomming arc for each demand node |
|
1446 |
for (int i = 0; i != int(demand_nodes.size()); ++i) { |
|
1447 |
Node v = demand_nodes[i]; |
|
1448 |
Cost c, min_cost = std::numeric_limits<Cost>::max(); |
|
1449 |
Arc min_arc = INVALID; |
|
1450 |
for (InArcIt a(_graph, v); a != INVALID; ++a) { |
|
1451 |
c = _cost[_arc_id[a]]; |
|
1452 |
if (c < min_cost) { |
|
1453 |
min_cost = c; |
|
1454 |
min_arc = a; |
|
1455 |
} |
|
1456 |
} |
|
1457 |
if (min_arc != INVALID) { |
|
1458 |
arc_vector.push_back(_arc_id[min_arc]); |
|
1459 |
} |
|
1460 |
} |
|
1461 |
} |
|
1462 |
} else { |
|
1463 |
// Find the min. cost outgoing arc for each supply node |
|
1464 |
for (int i = 0; i != int(supply_nodes.size()); ++i) { |
|
1465 |
Node u = supply_nodes[i]; |
|
1466 |
Cost c, min_cost = std::numeric_limits<Cost>::max(); |
|
1467 |
Arc min_arc = INVALID; |
|
1468 |
for (OutArcIt a(_graph, u); a != INVALID; ++a) { |
|
1469 |
c = _cost[_arc_id[a]]; |
|
1470 |
if (c < min_cost) { |
|
1471 |
min_cost = c; |
|
1472 |
min_arc = a; |
|
1473 |
} |
|
1474 |
} |
|
1475 |
if (min_arc != INVALID) { |
|
1476 |
arc_vector.push_back(_arc_id[min_arc]); |
|
1477 |
} |
|
1478 |
} |
|
1479 |
} |
|
1480 |
|
|
1481 |
// Perform heuristic initial pivots |
|
1482 |
for (int i = 0; i != int(arc_vector.size()); ++i) { |
|
1483 |
in_arc = arc_vector[i]; |
|
1484 |
if (_state[in_arc] * (_cost[in_arc] + _pi[_source[in_arc]] - |
|
1485 |
_pi[_target[in_arc]]) >= 0) continue; |
|
1486 |
findJoinNode(); |
|
1487 |
bool change = findLeavingArc(); |
|
1488 |
if (delta >= MAX) return false; |
|
1489 |
changeFlow(change); |
|
1490 |
if (change) { |
|
1491 |
updateTreeStructure(); |
|
1492 |
updatePotential(); |
|
1493 |
} |
|
1494 |
} |
|
1495 |
return true; |
|
1496 |
} |
|
1497 |
|
|
1403 | 1498 |
// Execute the algorithm |
1404 | 1499 |
ProblemType start(PivotRule pivot_rule) { |
1405 | 1500 |
// Select the pivot rule implementation |
1406 | 1501 |
switch (pivot_rule) { |
1407 | 1502 |
case FIRST_ELIGIBLE: |
1408 | 1503 |
return start<FirstEligiblePivotRule>(); |
... | ... |
@@ -1419,12 +1514,15 @@ |
1419 | 1514 |
} |
1420 | 1515 |
|
1421 | 1516 |
template <typename PivotRuleImpl> |
1422 | 1517 |
ProblemType start() { |
1423 | 1518 |
PivotRuleImpl pivot(*this); |
1424 | 1519 |
|
1520 |
// Perform heuristic initial pivots |
|
1521 |
if (!initialPivots()) return UNBOUNDED; |
|
1522 |
|
|
1425 | 1523 |
// Execute the Network Simplex algorithm |
1426 | 1524 |
while (pivot.findEnteringArc()) { |
1427 | 1525 |
findJoinNode(); |
1428 | 1526 |
bool change = findLeavingArc(); |
1429 | 1527 |
if (delta >= MAX) return UNBOUNDED; |
1430 | 1528 |
changeFlow(change); |
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