[Lemon-commits] [lemon_svn] jacint: r127 - hugo/trunk/src/work/jacint
Lemon SVN
svn at lemon.cs.elte.hu
Mon Nov 6 20:37:29 CET 2006
Author: jacint
Date: Wed Feb 18 15:43:01 2004
New Revision: 127
Added:
hugo/trunk/src/work/jacint/preflow_hl2.h
Log:
egyfajta preflow
Added: hugo/trunk/src/work/jacint/preflow_hl2.h
==============================================================================
--- (empty file)
+++ hugo/trunk/src/work/jacint/preflow_hl2.h Wed Feb 18 15:43:01 2004
@@ -0,0 +1,403 @@
+// -*- 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
+heuristic that the bound b on the active nodes is not increased
+only when b=0, when we put b=2*n-2.
+
+'A' is a parameter for the empty_level heuristic
+
+Member functions:
+
+void run() : runs the algorithm
+
+ The following functions should be used after run() was already run.
+
+T maxflow() : returns the value of a maximum flow
+
+T flowonedge(EdgeIt e) : for a fixed maximum flow x it returns x(e)
+
+FlowMap allflow() : 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
+ 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
+ maximum min cut. M should be a map of bools initialized to false.
+
+*/
+
+#ifndef PREFLOW_HL2_H
+#define PREFLOW_HL2_H
+
+#define A 1
+
+#include <vector>
+#include <stack>
+#include <queue>
+
+namespace marci {
+
+ template <typename Graph, typename T,
+ typename FlowMap=typename Graph::EdgeMap<T>, typename CapMap=typename Graph::EdgeMap<T>,
+ typename IntMap=typename Graph::NodeMap<int>, typename TMap=typename Graph::NodeMap<T> >
+ class preflow_hl2 {
+
+ typedef typename Graph::NodeIt NodeIt;
+ typedef typename Graph::EdgeIt EdgeIt;
+ typedef typename Graph::EachNodeIt EachNodeIt;
+ typedef typename Graph::OutEdgeIt OutEdgeIt;
+ typedef typename Graph::InEdgeIt InEdgeIt;
+
+ Graph& G;
+ NodeIt s;
+ NodeIt t;
+ FlowMap flow;
+ CapMap& capacity;
+ T value;
+
+ public:
+
+ preflow_hl2(Graph& _G, NodeIt _s, NodeIt _t, CapMap& _capacity) :
+ G(_G), s(_s), t(_t), flow(_G, 0), 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);
+ TMap excess(G);
+
+ std::vector<int> numb(n+1);
+ /*
+ The number of nodes on level i < n. It is
+ initialized to n+1, because of the reverse_bfs-part.
+ */
+
+ std::vector<std::stack<NodeIt> > stack(2*n-1);
+ //Stack of the active nodes in level i.
+
+
+ /*Reverse_bfs from t, to find the starting level.*/
+ level.set(t,0);
+ std::queue<NodeIt> bfs_queue;
+ bfs_queue.push(t);
+
+ while (!bfs_queue.empty()) {
+
+ NodeIt v=bfs_queue.front();
+ bfs_queue.pop();
+ int l=level.get(v)+1;
+
+ for(InEdgeIt e=G.template first<InEdgeIt>(v); e.valid(); ++e) {
+ NodeIt w=G.tail(e);
+ if ( level.get(w) == n ) {
+ bfs_queue.push(w);
+ ++numb[l];
+ level.set(w, l);
+ }
+ }
+ }
+
+ level.set(s,n);
+
+
+
+ /* Starting flow. It is everywhere 0 at the moment. */
+ for(OutEdgeIt e=G.template first<OutEdgeIt>(s); e.valid(); ++e)
+ {
+ if ( capacity.get(e) == 0 ) continue;
+ NodeIt w=G.head(e);
+ if ( w!=s ) {
+ if ( excess.get(w) == 0 && w!=t ) stack[level.get(w)].push(w);
+ flow.set(e, capacity.get(e));
+ excess.set(w, excess.get(w)+capacity.get(e));
+ }
+ }
+
+ /*
+ 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 {
+
+ no_end=true;
+
+ NodeIt w=stack[b].top(); //w is a highest label active node.
+ stack[b].pop();
+ int lev=level.get(w);
+ int exc=excess.get(w);
+ int newlevel=2*n-2; //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( lev > level.get(v) ) {
+ /*Push is allowed now*/
+
+ if ( excess.get(v)==0 && v != s && v !=t )
+ stack[level.get(v)].push(v);
+ /*v becomes active.*/
+
+ int cap=capacity.get(e);
+ int flo=flow.get(e);
+ int remcap=cap-flo;
+
+ if ( remcap >= exc ) {
+ /*A nonsaturating push.*/
+
+ flow.set(e, flo+exc);
+ excess.set(v, excess.get(v)+exc);
+ exc=0;
+ break;
+
+ } else {
+ /*A saturating push.*/
+
+ flow.set(e, cap );
+ excess.set(v, excess.get(v)+remcap);
+ exc-=remcap;
+ }
+ } else if ( newlevel > level.get(v) ) newlevel = level.get(v);
+
+ } //for out edges wv
+
+
+ if ( exc > 0 ) {
+ for( InEdgeIt e=G.template first<InEdgeIt>(w); e.valid(); ++e) {
+
+ if( flow.get(e) == 0 ) continue;
+ NodeIt v=G.tail(e);
+ //e=vw
+
+ if( lev > level.get(v) ) {
+ /*Push is allowed now*/
+
+ if ( excess.get(v)==0 && v != s && v !=t)
+ stack[level.get(v)].push(v);
+ /*v becomes active.*/
+
+ int flo=flow.get(e);
+
+ if ( flo >= exc ) {
+ /*A nonsaturating push.*/
+
+ flow.set(e, flo-exc);
+ excess.set(v, excess.get(v)+exc);
+ exc=0;
+ break;
+ } else {
+ /*A saturating push.*/
+
+ excess.set(v, excess.get(v)+flo);
+ exc-=flo;
+ flow.set(e,0);
+ }
+ } 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);
+
+
+ /*
+ Relabel
+ */
+
+ if ( exc > 0 ) {
+ //now 'lev' is the old level of w
+ 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() {
+ return value;
+ }
+
+
+
+ /*
+ 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) {
+ return flow.get(e);
+ }
+
+
+
+ /*
+ Returns the maximum flow x found by the algorithm.
+ */
+
+ FlowMap allflow() {
+ return flow;
+ }
+
+
+
+
+ /*
+ Returns the minimum min cut, by a bfs from s in the residual graph.
+ */
+
+ template<typename CutMap>
+ 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);
+ }
+ }
+
+ for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
+ 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) {
+
+ std::queue<NodeIt> queue;
+
+ M.set(t,true);
+ queue.push(t);
+
+ while (!queue.empty()) {
+ NodeIt w=queue.front();
+ queue.pop();
+
+ for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
+ NodeIt v=G.tail(e);
+ if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
+ queue.push(v);
+ M.set(v, true);
+ }
+ }
+
+ for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
+ NodeIt v=G.head(e);
+ if (!M.get(v) && flow.get(e) > 0 ) {
+ queue.push(v);
+ M.set(v, true);
+ }
+ }
+ }
+
+ for(EachNodeIt v=G.template first<EachNodeIt>() ; v.valid(); ++v) {
+ M.set(v, !M.get(v));
+ }
+
+ }
+
+
+
+ template<typename CutMap>
+ void min_mincut(CutMap& M) {
+ mincut(M);
+ }
+
+
+
+ };
+}//namespace marci
+#endif
+
+
+
+
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