lemon-0.x: comparison src/work/jacint/preflow

equal deleted inserted replaced

-:709167d7212b
+:1469a2bdf3e1
 // -*- C++ -*-
 /*
 preflow_hl2.h
 by jacint.
 Runs the highest label variant of the preflow push algorithm with
-running time O(n^2\sqrt(m)), with the 'empty level' and with the
+running time O(n^2\sqrt(m)).
-heuristic that the bound b on the active nodes is not increased
-only when b=0, when we put b=2*n-2.
+Heuristics:
-'A' is a parameter for the empty_level heuristic
+gap: we iterate through the nodes for finding the nodes above
+the gap and under level n. So it is quite slow.
-Member functions:
+numb: we maintain the number of nodes in level i.
+highest label
-void run() : runs the algorithm
+'A' is a parameter for the gap, we only upgrade the nodes to level n,
-The following functions should be used after run() was already run.
+if the gap is under A*n.
-T maxflow() : returns the value of a maximum flow
+The constructor runs the algorithm.
-T flowonedge(EdgeIt e) : for a fixed maximum flow x it returns x(e)
+Members:
-FlowMap allflow() : returns the fixed maximum flow x
+T maxFlow() : returns the value of a maximum flow
-void mincut(CutMap& M) : sets M to the characteristic vector of a
+T flowOnEdge(EdgeIt e) : for a fixed maximum flow x it returns x(e)
+FlowMap Flow() : returns the fixed maximum flow x
+void minCut(CutMap& M) : sets M to the characteristic vector of a
 minimum cut. M should be a map of bools initialized to false.
-void min_mincut(CutMap& M) : sets M to the characteristic vector of the
+void minMinCut(CutMap& M) : sets M to the characteristic vector of the
 minimum min cut. M should be a map of bools initialized to false.
-void max_mincut(CutMap& M) : sets M to the characteristic vector of the
+void maxMinCut(CutMap& M) : sets M to the characteristic vector of the
 maximum min cut. M should be a map of bools initialized to false.
 */
 #ifndef PREFLOW_HL2_H
 #define PREFLOW_HL2_H
-#define A 1
+#define A .9
 #include <vector>
 #include <stack>
 #include <queue>
 namespace hugo {
 template <typename Graph, typename T,
-typename FlowMap=typename Graph::EdgeMap<T>, typename CapMap=typename Graph::EdgeMap<T>,
+typename FlowMap=typename Graph::EdgeMap<T>,
-typename IntMap=typename Graph::NodeMap<int>, typename TMap=typename Graph::NodeMap<T> >
+typename CapMap=typename Graph::EdgeMap<T> >
 class preflow_hl2 {
 typedef typename Graph::NodeIt NodeIt;
 typedef typename Graph::EdgeIt EdgeIt;
 typedef typename Graph::EachNodeIt EachNodeIt;
 T value;
 public:
 preflow_hl2(Graph& _G, NodeIt _s, NodeIt _t, CapMap& _capacity) :
-G(_G), s(_s), t(_t), flow(_G, 0), capacity(_capacity) { }
+G(_G), s(_s), t(_t), flow(_G), capacity(_capacity) {
-void run() {
-bool no_end=true;
 int n=G.nodeNum();
 int b=n-2;
 /*
 	b is a bound on the highest level of an active node.
-	In the beginning it is at most n-2.
 */
-IntMap level(G,n);
+typename Graph::NodeMap<int> level(G,n);
-TMap excess(G);
+typename Graph::NodeMap<T> excess(G);
 std::vector<int> numb(n);
 /*
 	The number of nodes on level i < n. It is
 	initialized to n+1, because of the reverse_bfs-part.
 */
 	    ++numb[l];
 	    level.set(w, l);
 	  }
 	}
 }
 level.set(s,n);
 /* Starting flow. It is everywhere 0 at the moment. */
 	    if ( excess.get(w) == 0 && w!=t ) stack[level.get(w)].push(w);
 	    flow.set(e, c);
 	    excess.set(w, excess.get(w)+c);
 	  }
 	}
 /*
 	 End of preprocessing
 */
 /*
 	Push/relabel on the highest level active nodes.
 */
 /*While there exists an active node.*/
 while (b) {
 	if ( stack[b].empty() ) {
-	  if ( b==1 ) {
-	    if ( !no_end ) break;
-	    else {
-	      b=2*n-2;
-	      no_end=false;
-	    }
-	  }
 	  --b;
-	} else {
+	  continue;
+	}
-	  no_end=true;
+	NodeIt w=stack[b].top();
-	  NodeIt w=stack[b].top();        //w is a highest label active node.
+	stack[b].pop();
-	  stack[b].pop();
+	int lev=level.get(w);
-	  int lev=level.get(w);
+	T exc=excess.get(w);
-	  int exc=excess.get(w);
+	int newlevel=2*n;      //In newlevel we bound the next level of w.
-	  int newlevel=2*n;      //In newlevel we bound the next level of w.
-	  //  if ( level.get(w) < n ) { //Nem tudom ez mukodik-e
 	  for(OutEdgeIt e=G.template first<OutEdgeIt>(w); e.valid(); ++e) {
 	    if ( flow.get(e) == capacity.get(e) ) continue;
 	    NodeIt v=G.head(e);
 	    //e=wv
 	      if ( excess.get(v)==0 && v != s && v !=t )
 		stack[level.get(v)].push(v);
 	      /*v becomes active.*/
-	      int cap=capacity.get(e);
+	      T cap=capacity.get(e);
-	      int flo=flow.get(e);
+	      T flo=flow.get(e);
-	      int remcap=cap-flo;
+	      T remcap=cap-flo;
 	      if ( remcap >= exc ) {
 		/*A nonsaturating push.*/
 		flow.set(e, flo+exc);
 	      if ( excess.get(v)==0 && v != s && v !=t)
 		stack[level.get(v)].push(v);
 	      /*v becomes active.*/
-	      int flo=flow.get(e);
+	      T flo=flow.get(e);
 	      if ( flo >= exc ) {
 		/*A nonsaturating push.*/
 		flow.set(e, flo-exc);
 	    } else if ( newlevel > level.get(v) ) newlevel = level.get(v);
 	  } //for in edges vw
 	} // if w still has excess after the out edge for cycle
-	  excess.set(w, exc);
+	excess.set(w, exc);
+	/*
+	  Relabel
+	*/
+	if ( exc > 0 ) {
+	  //now 'lev' is the old level of w
+	  level.set(w,++newlevel);
+	  if ( lev < n ) {
-	  /*
+	    --numb[lev];
-	    Relabel
-	  */
+	    if ( !numb[lev] && lev < A*n ) {  //If the level of w gets empty.
+	      for (EachNodeIt v=G.template first<EachNodeIt>(); v.valid() ; ++v) {
+		if (level.get(v) > lev && level.get(v) < n ) level.set(v,n);
+	      }
+	      for (int i=lev+1 ; i!=n ; ++i) numb[i]=0;
+	      if ( newlevel < n ) newlevel=n;
+	    } else {
+	      if ( newlevel < n ) ++numb[newlevel];
+	    }
+	  }
-	  if ( exc > 0 ) {
+	  stack[newlevel].push(w);
-	    //now 'lev' is the old level of w
+	  b=newlevel;
-	    level.set(w,++newlevel);
+	}
-	    if ( lev < n ) {
-	      --numb[lev];
-	      if ( !numb[lev] && lev < A*n ) {  //If the level of w gets empty.
-		for (EachNodeIt v=G.template first<EachNodeIt>(); v.valid() ; ++v) {
-		  if (level.get(v) > lev && level.get(v) < n ) level.set(v,n);
-		}
-		for (int i=lev+1 ; i!=n ; ++i) numb[i]=0;
-		if ( newlevel < n ) newlevel=n;
-	      } else {
-		if ( newlevel < n ) ++numb[newlevel];
-	      }
-	    }
-	    stack[newlevel].push(w);
-	  }
-	} // if stack[b] is nonempty
 } // while(b)
 value = excess.get(t);
 /*Max flow value.*/
 } //void run()
 /*
 Returns the maximum value of a flow.
 */
-T maxflow() {
+T maxFlow() {
 return value;
 }
 /*
-For the maximum flow x found by the algorithm, it returns the flow value on Edge e, i.e. x(e).
+For the maximum flow x found by the algorithm,
+it returns the flow value on edge e, i.e. x(e).
 */
-T flowonedge(EdgeIt e) {
+T flowOnEdge(const EdgeIt e) {
 return flow.get(e);
 }
 /*
 Returns the maximum flow x found by the algorithm.
 */
-FlowMap allflow() {
+FlowMap Flow() {
 return flow;
 }
 /*
 Returns the minimum min cut, by a bfs from s in the residual graph.
 */
 template<typename CutMap>
-void mincut(CutMap& M) {
+void minCut(CutMap& M) {
 std::queue<NodeIt> queue;
 M.set(s,true);
 queue.push(s);
 while (!queue.empty()) {
 NodeIt w=queue.front();
 	queue.pop();
 	for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
 	  NodeIt v=G.head(e);
 	  if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
 	    queue.push(v);
 	    M.set(v, true);
 	  NodeIt v=G.tail(e);
 	  if (!M.get(v) && flow.get(e) > 0 ) {
 	    queue.push(v);
 	    M.set(v, true);
 	  }
 	}
 }
 }
 /*
 Returns the maximum min cut, by a reverse bfs
 from t in the residual graph.
 */
 template<typename CutMap>
-void max_mincut(CutMap& M) {
+void maxMinCut(CutMap& M) {
 std::queue<NodeIt> queue;
 M.set(t,true);
 queue.push(t);
 }
 template<typename CutMap>
-void min_mincut(CutMap& M) {
+void minMinCut(CutMap& M) {
-mincut(M);
+minCut(M);
 }
 };
-}//namespace hugo
+}//namespace marci
 #endif

changeset 111	3a5ebcd91d37
parent 105	a3c73e9b9b2e