Changeset 1222:a3fb216a267d in lemon-0.x for src/lemon/preflow.h

Timestamp:

03/17/05 11:43:57 (19 years ago)

Author:

Alpar Juttner

Branch:

default

Phase:

public

Convert:

svn:c9d7d8f5-90d6-0310-b91f-818b3a526b0e/lemon/trunk@1642

Message:

The first step toward function type interface to Preflow alg:

• Naming changed to be closer in style to the BFD/DFS/Dijkstra triplet.

File:

• src/lemon/preflow.h (modified) (39 diffs)

src/lemon/preflow.h

@@ -38 +38 @@
   ///This class provides an implementation of the \e preflow \e
   ///algorithm producing a flow of maximum value in a directed
-  ///graph. The preflow algorithms are the fastest max flow algorithms
+  ///graph. The preflow algorithms are the fastest known max flow algorithms
   ///up to now. The \e source node, the \e target node, the \e
   ///capacity of the edges and the \e starting \e flow value of the
   ///edges should be passed to the algorithm through the
   ///constructor. It is possible to change these quantities using the
-  ///functions \ref setSource, \ref setTarget, \ref setCap and \ref
+  ///functions \ref source, \ref target, \ref setCap and \ref
   ///setFlow.
   ///
@@ -56 +56 @@
   ///\param Graph The directed graph type the algorithm runs on.
   ///\param Num The number type of the capacities and the flow values.
-  ///\param CapMap The capacity map type.
+  ///\param CapacityMap The capacity map type.
   ///\param FlowMap The flow map type.
   ///
   ///\author Jacint Szabo 
   template <typename Graph, typename Num,
-            typename CapMap=typename Graph::template EdgeMap<Num>,
+            typename CapacityMap=typename Graph::template EdgeMap<Num>,
             typename FlowMap=typename Graph::template EdgeMap<Num> >
   class Preflow {
@@ -74 +74 @@
     typedef typename std::vector<Node> VecNode;
 
-    const Graph* g;
-    Node s;
-    Node t;
-    const CapMap* capacity;
-    FlowMap* flow;
-    int n;      //the number of nodes of G
+    const Graph* _g;
+    Node _source;
+    Node _target;
+    const CapacityMap* _capacity;
+    FlowMap* _flow;
+    int _node_num;      //the number of nodes of G
     
     typename Graph::template NodeMap<int> level;  
@@ -92 +92 @@
     ///Indicates the property of the starting flow map.
 
-    ///Indicates the property of the starting flow map. The meanings are as follows:
+    ///Indicates the property of the starting flow map.
+    ///The meanings are as follows:
     ///- \c ZERO_FLOW: constant zero flow
     ///- \c GEN_FLOW: any flow, i.e. the sum of the in-flows equals to
@@ -112 +113 @@
     ///Indicates the state of the preflow algorithm.
 
-    ///Indicates the state of the preflow algorithm. The meanings are as follows:
-    ///- \c AFTER_NOTHING: before running the algorithm or at an unspecified state.
+    ///Indicates the state of the preflow algorithm.
+    ///The meanings are as follows:
+    ///- \c AFTER_NOTHING: before running the algorithm or
+    ///  at an unspecified state.
     ///- \c AFTER_PREFLOW_PHASE_1: right after running \c phase1
     ///- \c AFTER_PREFLOW_PHASE_2: after running \ref phase2()
@@ -134 +137 @@
     ///\param _s The source node.
     ///\param _t The target node.
-    ///\param _capacity The capacity of the edges. 
-    ///\param _flow The flow of the edges. 
+    ///\param _cap The capacity of the edges. 
+    ///\param _f The flow of the edges. 
     ///Except the graph, all of these parameters can be reset by
-    ///calling \ref setSource, \ref setTarget, \ref setCap and \ref
+    ///calling \ref source, \ref target, \ref setCap and \ref
     ///setFlow, resp.
-      Preflow(const Graph& _G, Node _s, Node _t, 
-              const CapMap& _capacity, FlowMap& _flow) :
-        g(&_G), s(_s), t(_t), capacity(&_capacity),
-        flow(&_flow), n(countNodes(_G)), level(_G), excess(_G,0), 
+      Preflow(const Graph& _gr, Node _s, Node _t, 
+              const CapacityMap& _cap, FlowMap& _f) :
+        _g(&_gr), _source(_s), _target(_t), _capacity(&_cap),
+        _flow(&_f), _node_num(countNodes(_gr)), level(_gr), excess(_gr,0), 
         flow_prop(NO_FLOW), status(AFTER_NOTHING) { }
 
@@ -205 +208 @@
     void phase1()
     {
-      int heur0=(int)(H0*n);  //time while running 'bound decrease'
-      int heur1=(int)(H1*n);  //time while running 'highest label'
+      int heur0=(int)(H0*_node_num);  //time while running 'bound decrease'
+      int heur1=(int)(H1*_node_num);  //time while running 'highest label'
       int heur=heur1;         //starting time interval (#of relabels)
       int numrelabel=0;
@@ -217 +220 @@
       //nodes are above bound b.
 
-      int k=n-2;  //bound on the highest level under n containing a node
+      int k=_node_num-2;  //bound on the highest level under n containing a node
       int b=k;    //bound on the highest level under n of an active node
 
-      VecNode first(n, INVALID);
-      NNMap next(*g, INVALID);
-
-      NNMap left(*g, INVALID);
-      NNMap right(*g, INVALID);
-      VecNode level_list(n,INVALID);
+      VecNode first(_node_num, INVALID);
+      NNMap next(*_g, INVALID);
+
+      NNMap left(*_g, INVALID);
+      NNMap right(*_g, INVALID);
+      VecNode level_list(_node_num,INVALID);
       //List of the nodes in level i<n, set to n.
 
@@ -272 +275 @@
     //   stack 'active' on the active nodes on level i      
     //   runs heuristic 'highest label' for H1*n relabels
-    //   runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label'
+    //   runs heuristic 'bound decrease' for H0*n relabels,
+    //        starts with 'highest label'
     //   Parameters H0 and H1 are initialized to 20 and 1.
 
@@ -288 +292 @@
     {
 
-      int k=n-2;  //bound on the highest level under n containing a node
+      int k=_node_num-2;  //bound on the highest level under n containing a node
       int b=k;    //bound on the highest level under n of an active node
 
     
-      VecNode first(n, INVALID);
-      NNMap next(*g, INVALID); 
-      level.set(s,0);
+      VecNode first(_node_num, INVALID);
+      NNMap next(*_g, INVALID); 
+      level.set(_source,0);
       std::queue<Node> bfs_queue;
-      bfs_queue.push(s);
+      bfs_queue.push(_source);
 
       while ( !bfs_queue.empty() ) {
@@ -304 +308 @@
         int l=level[v]+1;
 
-        for(InEdgeIt e(*g,v); e!=INVALID; ++e) {
-          if ( (*capacity)[e] <= (*flow)[e] ) continue;
-          Node u=g->source(e);
-          if ( level[u] >= n ) {
+        for(InEdgeIt e(*_g,v); e!=INVALID; ++e) {
+          if ( (*_capacity)[e] <= (*_flow)[e] ) continue;
+          Node u=_g->source(e);
+          if ( level[u] >= _node_num ) {
             bfs_queue.push(u);
             level.set(u, l);
@@ -317 +321 @@
         }
 
-        for(OutEdgeIt e(*g,v); e!=INVALID; ++e) {
-          if ( 0 >= (*flow)[e] ) continue;
-          Node u=g->target(e);
-          if ( level[u] >= n ) {
+        for(OutEdgeIt e(*_g,v); e!=INVALID; ++e) {
+          if ( 0 >= (*_flow)[e] ) continue;
+          Node u=_g->target(e);
+          if ( level[u] >= _node_num ) {
             bfs_queue.push(u);
             level.set(u, l);
@@ -330 +334 @@
         }
       }
-      b=n-2;
+      b=_node_num-2;
 
       while ( true ) {
@@ -360 +364 @@
     /// the maximum flow already after running \ref phase1.
     Num flowValue() const {
-      return excess[t];
+      return excess[_target];
     }
 
@@ -376 +380 @@
       switch ( status ) {
         case AFTER_PREFLOW_PHASE_1:
-        for(NodeIt v(*g); v!=INVALID; ++v) {
-          if (level[v] < n) {
+        for(NodeIt v(*_g); v!=INVALID; ++v) {
+          if (level[v] < _node_num) {
             M.set(v, false);
           } else {
@@ -403 +407 @@
 
       std::queue<Node> queue;
-      M.set(s,true);
+      M.set(_source,true);
       queue.push(s);
       
@@ -410 +414 @@
         queue.pop();
         
-        for(OutEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-          Node v=g->target(e);
-          if (!M[v] && (*flow)[e] < (*capacity)[e] ) {
+        for(OutEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+          Node v=_g->target(e);
+          if (!M[v] && (*_flow)[e] < (*_capacity)[e] ) {
             queue.push(v);
             M.set(v, true);
@@ -418 +422 @@
         }
         
-        for(InEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-          Node v=g->source(e);
-          if (!M[v] && (*flow)[e] > 0 ) {
+        for(InEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+          Node v=_g->source(e);
+          if (!M[v] && (*_flow)[e] > 0 ) {
             queue.push(v);
             M.set(v, true);
@@ -437 +441 @@
     void maxMinCut(_CutMap& M) const {
 
-      for(NodeIt v(*g) ; v!=INVALID; ++v) M.set(v, true);
+      for(NodeIt v(*_g) ; v!=INVALID; ++v) M.set(v, true);
 
       std::queue<Node> queue;
 
-      M.set(t,false);
-      queue.push(t);
+      M.set(_target,false);
+      queue.push(_target);
 
       while (!queue.empty()) {
@@ -448 +452 @@
         queue.pop();
 
-        for(InEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-          Node v=g->source(e);
-          if (M[v] && (*flow)[e] < (*capacity)[e] ) {
+        for(InEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+          Node v=_g->source(e);
+          if (M[v] && (*_flow)[e] < (*_capacity)[e] ) {
             queue.push(v);
             M.set(v, false);
@@ -456 +460 @@
         }
 
-        for(OutEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-          Node v=g->target(e);
-          if (M[v] && (*flow)[e] > 0 ) {
+        for(OutEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+          Node v=_g->target(e);
+          if (M[v] && (*_flow)[e] > 0 ) {
             queue.push(v);
             M.set(v, false);
@@ -470 +474 @@
     ///Sets the source node to \c _s.
     /// 
-    void setSource(Node _s) { 
-      s=_s; 
+    void source(Node _s) { 
+      _source=_s; 
       if ( flow_prop != ZERO_FLOW ) flow_prop=NO_FLOW;
       status=AFTER_NOTHING; 
     }
 
+    ///Returns the source node.
+
+    ///Returns the source node.
+    /// 
+    Node source() const { 
+      return _source;
+    }
+
     ///Sets the target node to \c _t.
 
     ///Sets the target node to \c _t.
     ///
-    void setTarget(Node _t) { 
-      t=_t; 
+    void target(Node _t) { 
+      _target=_t; 
       if ( flow_prop == GEN_FLOW ) flow_prop=PRE_FLOW;
       status=AFTER_NOTHING; 
     }
 
+    ///Returns the target node.
+
+    ///Returns the target node.
+    /// 
+    Node target() const { 
+      return _target;
+    }
+
     /// Sets the edge map of the capacities to _cap.
 
     /// Sets the edge map of the capacities to _cap.
     /// 
-    void setCap(const CapMap& _cap) { 
-      capacity=&_cap; 
+    void capacityMap(const CapacityMap& _cap) { 
+      _capacity=&_cap; 
       status=AFTER_NOTHING; 
+    }
+    /// Returns a reference to to capacity map.
+
+    /// Returns a reference to to capacity map.
+    /// 
+    const CapacityMap &capacityMap() const { 
+      return *_capacity;
     }
 
@@ -499 +526 @@
     /// Sets the edge map of the flows to _flow.
     /// 
-    void setFlow(FlowMap& _flow) { 
-      flow=&_flow; 
+    void flowMap(FlowMap& _f) { 
+      _flow=&_f; 
       flow_prop=NO_FLOW;
       status=AFTER_NOTHING; 
     }
-
+     
+    /// Returns a reference to to flow map.
+
+    /// Returns a reference to to flow map.
+    /// 
+    const FlowMap &flowMap() const { 
+      return *_flow;
+    }
 
   private:
@@ -512 +546 @@
       int lev=level[w];
       Num exc=excess[w];
-      int newlevel=n;       //bound on the next level of w
-
-      for(OutEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-        if ( (*flow)[e] >= (*capacity)[e] ) continue;
-        Node v=g->target(e);
+      int newlevel=_node_num;       //bound on the next level of w
+
+      for(OutEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+        if ( (*_flow)[e] >= (*_capacity)[e] ) continue;
+        Node v=_g->target(e);
 
         if( lev > level[v] ) { //Push is allowed now
           
-          if ( excess[v]<=0 && v!=t && v!=s ) {
+          if ( excess[v]<=0 && v!=_target && v!=_source ) {
             next.set(v,first[level[v]]);
             first[level[v]]=v;
           }
 
-          Num cap=(*capacity)[e];
-          Num flo=(*flow)[e];
+          Num cap=(*_capacity)[e];
+          Num flo=(*_flow)[e];
           Num remcap=cap-flo;
           
           if ( remcap >= exc ) { //A nonsaturating push.
             
-            flow->set(e, flo+exc);
+            _flow->set(e, flo+exc);
             excess.set(v, excess[v]+exc);
             exc=0;
@@ -537 +571 @@
 
           } else { //A saturating push.
-            flow->set(e, cap);
+            _flow->set(e, cap);
             excess.set(v, excess[v]+remcap);
             exc-=remcap;
@@ -545 +579 @@
 
       if ( exc > 0 ) {
-        for(InEdgeIt e(*g,w) ; e!=INVALID; ++e) {
-          
-          if( (*flow)[e] <= 0 ) continue;
-          Node v=g->source(e);
+        for(InEdgeIt e(*_g,w) ; e!=INVALID; ++e) {
+          
+          if( (*_flow)[e] <= 0 ) continue;
+          Node v=_g->source(e);
 
           if( lev > level[v] ) { //Push is allowed now
 
-            if ( excess[v]<=0 && v!=t && v!=s ) {
+            if ( excess[v]<=0 && v!=_target && v!=_source ) {
               next.set(v,first[level[v]]);
               first[level[v]]=v;
             }
 
-            Num flo=(*flow)[e];
+            Num flo=(*_flow)[e];
 
             if ( flo >= exc ) { //A nonsaturating push.
 
-              flow->set(e, flo-exc);
+              _flow->set(e, flo-exc);
               excess.set(v, excess[v]+exc);
               exc=0;
@@ -569 +603 @@
               excess.set(v, excess[v]+flo);
               exc-=flo;
-              flow->set(e,0);
+              _flow->set(e,0);
             }
           } else if ( newlevel > level[v] ) newlevel = level[v];
@@ -586 +620 @@
                         VecNode& level_list, NNMap& left, NNMap& right)
     {
-      for(NodeIt v(*g); v!=INVALID; ++v) level.set(v,n);
+      for(NodeIt v(*_g); v!=INVALID; ++v) level.set(v,_node_num);
       std::queue<Node> bfs_queue;
       
@@ -592 +626 @@
         //Reverse_bfs from t in the residual graph,
         //to find the starting level.
-        level.set(t,0);
-        bfs_queue.push(t);
+        level.set(_target,0);
+        bfs_queue.push(_target);
         
         while ( !bfs_queue.empty() ) {
@@ -601 +635 @@
           int l=level[v]+1;
           
-          for(InEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-            if ( (*capacity)[e] <= (*flow)[e] ) continue;
-            Node w=g->source(e);
-            if ( level[w] == n && w != s ) {
+          for(InEdgeIt e(*_g,v) ; e!=INVALID; ++e) {
+            if ( (*_capacity)[e] <= (*_flow)[e] ) continue;
+            Node w=_g->source(e);
+            if ( level[w] == _node_num && w != _source ) {
               bfs_queue.push(w);
               Node z=level_list[l];
@@ -614 +648 @@
           }
           
-          for(OutEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-            if ( 0 >= (*flow)[e] ) continue;
-            Node w=g->target(e);
-            if ( level[w] == n && w != s ) {
+          for(OutEdgeIt e(*_g,v) ; e!=INVALID; ++e) {
+            if ( 0 >= (*_flow)[e] ) continue;
+            Node w=_g->target(e);
+            if ( level[w] == _node_num && w != _source ) {
               bfs_queue.push(w);
               Node z=level_list[l];
@@ -632 +666 @@
       switch (flow_prop) {
         case NO_FLOW:  
-        for(EdgeIt e(*g); e!=INVALID; ++e) flow->set(e,0);
+        for(EdgeIt e(*_g); e!=INVALID; ++e) _flow->set(e,0);
         case ZERO_FLOW:
-        for(NodeIt v(*g); v!=INVALID; ++v) excess.set(v,0);
+        for(NodeIt v(*_g); v!=INVALID; ++v) excess.set(v,0);
         
         //Reverse_bfs from t, to find the starting level.
-        level.set(t,0);
-        bfs_queue.push(t);
+        level.set(_target,0);
+        bfs_queue.push(_target);
         
         while ( !bfs_queue.empty() ) {
@@ -646 +680 @@
           int l=level[v]+1;
           
-          for(InEdgeIt e(*g,v) ; e!=INVALID; ++e) {
-            Node w=g->source(e);
-            if ( level[w] == n && w != s ) {
+          for(InEdgeIt e(*_g,v) ; e!=INVALID; ++e) {
+            Node w=_g->source(e);
+            if ( level[w] == _node_num && w != _source ) {
               bfs_queue.push(w);
               Node z=level_list[l];
@@ -660 +694 @@
         
         //the starting flow
-        for(OutEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-          Num c=(*capacity)[e];
+        for(OutEdgeIt e(*_g,_source) ; e!=INVALID; ++e) {
+          Num c=(*_capacity)[e];
           if ( c <= 0 ) continue;
-          Node w=g->target(e);
-          if ( level[w] < n ) {
-            if ( excess[w] <= 0 && w!=t ) { //putting into the stack
+          Node w=_g->target(e);
+          if ( level[w] < _node_num ) {
+            if ( excess[w] <= 0 && w!=_target ) { //putting into the stack
               next.set(w,first[level[w]]);
               first[level[w]]=w;
             }
-            flow->set(e, c);
+            _flow->set(e, c);
             excess.set(w, excess[w]+c);
           }
@@ -676 +710 @@
 
         case GEN_FLOW:
-        for(NodeIt v(*g); v!=INVALID; ++v) excess.set(v,0);
+        for(NodeIt v(*_g); v!=INVALID; ++v) excess.set(v,0);
         {
           Num exc=0;
-          for(InEdgeIt e(*g,t) ; e!=INVALID; ++e) exc+=(*flow)[e];
-          for(OutEdgeIt e(*g,t) ; e!=INVALID; ++e) exc-=(*flow)[e];
-          excess.set(t,exc);
+          for(InEdgeIt e(*_g,_target) ; e!=INVALID; ++e) exc+=(*_flow)[e];
+          for(OutEdgeIt e(*_g,_target) ; e!=INVALID; ++e) exc-=(*_flow)[e];
+          excess.set(_target,exc);
         }
 
         //the starting flow
-        for(OutEdgeIt e(*g,s); e!=INVALID; ++e) {
-          Num rem=(*capacity)[e]-(*flow)[e];
+        for(OutEdgeIt e(*_g,_source); e!=INVALID; ++e)  {
+          Num rem=(*_capacity)[e]-(*_flow)[e];
           if ( rem <= 0 ) continue;
-          Node w=g->target(e);
-          if ( level[w] < n ) {
-            if ( excess[w] <= 0 && w!=t ) { //putting into the stack
+          Node w=_g->target(e);
+          if ( level[w] < _node_num ) {
+            if ( excess[w] <= 0 && w!=_target ) { //putting into the stack
               next.set(w,first[level[w]]);
               first[level[w]]=w;
             }   
-            flow->set(e, (*capacity)[e]);
+            _flow->set(e, (*_capacity)[e]);
             excess.set(w, excess[w]+rem);
           }
         }
         
-        for(InEdgeIt e(*g,s); e!=INVALID; ++e) {
-          if ( (*flow)[e] <= 0 ) continue;
-          Node w=g->source(e);
-          if ( level[w] < n ) {
-            if ( excess[w] <= 0 && w!=t ) {
+        for(InEdgeIt e(*_g,_source); e!=INVALID; ++e) {
+          if ( (*_flow)[e] <= 0 ) continue;
+          Node w=_g->source(e);
+          if ( level[w] < _node_num ) {
+            if ( excess[w] <= 0 && w!=_target ) {
               next.set(w,first[level[w]]);
               first[level[w]]=w;
             }  
-            excess.set(w, excess[w]+(*flow)[e]);
-            flow->set(e, 0);
+            excess.set(w, excess[w]+(*_flow)[e]);
+            _flow->set(e, 0);
           }
         }
@@ -715 +749 @@
         case PRE_FLOW:  
         //the starting flow
-        for(OutEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-          Num rem=(*capacity)[e]-(*flow)[e];
+        for(OutEdgeIt e(*_g,_source) ; e!=INVALID; ++e) {
+          Num rem=(*_capacity)[e]-(*_flow)[e];
           if ( rem <= 0 ) continue;
-          Node w=g->target(e);
-          if ( level[w] < n ) flow->set(e, (*capacity)[e]);
+          Node w=_g->target(e);
+          if ( level[w] < _node_num ) _flow->set(e, (*_capacity)[e]);
         }
         
-        for(InEdgeIt e(*g,s) ; e!=INVALID; ++e) {
-          if ( (*flow)[e] <= 0 ) continue;
-          Node w=g->source(e);
-          if ( level[w] < n ) flow->set(e, 0);
+        for(InEdgeIt e(*_g,_source) ; e!=INVALID; ++e) {
+          if ( (*_flow)[e] <= 0 ) continue;
+          Node w=_g->source(e);
+          if ( level[w] < _node_num ) _flow->set(e, 0);
         }
         
         //computing the excess
-        for(NodeIt w(*g); w!=INVALID; ++w) {
+        for(NodeIt w(*_g); w!=INVALID; ++w) {
           Num exc=0;
-          for(InEdgeIt e(*g,w); e!=INVALID; ++e) exc+=(*flow)[e];
-          for(OutEdgeIt e(*g,w); e!=INVALID; ++e) exc-=(*flow)[e];
+          for(InEdgeIt e(*_g,w); e!=INVALID; ++e) exc+=(*_flow)[e];
+          for(OutEdgeIt e(*_g,w); e!=INVALID; ++e) exc-=(*_flow)[e];
           excess.set(w,exc);
           
           //putting the active nodes into the stack
           int lev=level[w];
-            if ( exc > 0 && lev < n && Node(w) != t ) {
+            if ( exc > 0 && lev < _node_num && Node(w) != _target ) {
               next.set(w,first[lev]);
               first[lev]=w;
@@ -781 +815 @@
           Node v=level_list[++i];
           while ( v!=INVALID ) {
-            level.set(v,n);
+            level.set(v,_node_num);
             v=right[v];
           }
@@ -788 +822 @@
         }
 
-        level.set(w,n);
+        level.set(w,_node_num);
         b=lev-1;
         k=b;
@@ -795 +829 @@
       } else {
 
-        if ( newlevel == n ) level.set(w,n);
+        if ( newlevel == _node_num ) level.set(w,_node_num);
         else {
           level.set(w,++newlevel);