lemon-0.x: src/work/jacint/preflow_param.h@3c53698842dd (annotated)

jacint@109	1	// -- C++ --
jacint@109	2	/*
jacint@109	3	preflow_param.h
jacint@109	4	by jacint.
jacint@109	5
jacint@109	6	For testing the parameters H0, H1 of preflow.h
jacint@109	7
jacint@109	8	The constructor runs the algorithm.
jacint@109	9
jacint@109	10	Members:
jacint@109	11
jacint@109	12	T maxFlow() : returns the value of a maximum flow
jacint@109	13
jacint@109	14	T flowOnEdge(EdgeIt e) : for a fixed maximum flow x it returns x(e)
jacint@109	15
jacint@109	16	FlowMap Flow() : returns the fixed maximum flow x
jacint@109	17
jacint@109	18	void minMinCut(CutMap& M) : sets M to the characteristic vector of the
jacint@109	19	minimum min cut. M should be a map of bools initialized to false.
jacint@109	20
jacint@109	21	void maxMinCut(CutMap& M) : sets M to the characteristic vector of the
jacint@109	22	maximum min cut. M should be a map of bools initialized to false.
jacint@109	23
jacint@109	24	void minCut(CutMap& M) : fast function, sets M to the characteristic
jacint@109	25	vector of a minimum cut.
jacint@109	26
jacint@109	27	Different member from the other preflow_hl-s (here we have a member
jacint@109	28	'NodeMap<bool> cut').
jacint@109	29
jacint@109	30	CutMap minCut() : fast function, giving the characteristic
jacint@109	31	vector of a minimum cut.
jacint@109	32
jacint@109	33
jacint@109	34	*/
jacint@109	35
jacint@109	36	#ifndef PREFLOW_PARAM_H
jacint@109	37	#define PREFLOW_PARAM_H
jacint@109	38
jacint@109	39	#include <vector>
jacint@109	40	#include <queue>
jacint@109	41
jacint@109	42	#include <time_measure.h> //for test
jacint@109	43
jacint@109	44	namespace hugo {
jacint@109	45
jacint@109	46	template <typename Graph, typename T,
jacint@109	47	typename FlowMap=typename Graph::EdgeMap<T>,
jacint@109	48	typename CapMap=typename Graph::EdgeMap<T> >
jacint@109	49	class preflow_param {
jacint@109	50
jacint@109	51	typedef typename Graph::NodeIt NodeIt;
jacint@109	52	typedef typename Graph::EdgeIt EdgeIt;
jacint@109	53	typedef typename Graph::EachNodeIt EachNodeIt;
jacint@109	54	typedef typename Graph::OutEdgeIt OutEdgeIt;
jacint@109	55	typedef typename Graph::InEdgeIt InEdgeIt;
jacint@109	56
jacint@109	57	Graph& G;
jacint@109	58	NodeIt s;
jacint@109	59	NodeIt t;
jacint@109	60	FlowMap flow;
jacint@109	61	CapMap& capacity;
jacint@109	62	T value;
jacint@109	63	int H0;
jacint@109	64	int H1;
jacint@109	65
jacint@109	66	public:
jacint@109	67	double time;
jacint@109	68
jacint@109	69	preflow_param(Graph& _G, NodeIt _s, NodeIt _t, CapMap& _capacity,
jacint@109	70	int _H0, int _H1) :
jacint@109	71	G(_G), s(_s), t(_t), flow(_G, 0), capacity(_capacity), H0(_H0), H1(_H1) {
jacint@109	72
jacint@109	73	bool phase=0; //phase 0 is the 1st phase, phase 1 is the 2nd
jacint@109	74	int n=G.nodeNum();
jacint@109	75	int heur0=(int)(H0*n); //time while running 'bound decrease'
jacint@109	76	int heur1=(int)(H1*n); //time while running 'highest label'
jacint@109	77	int heur=heur1; //starting time interval (#of relabels)
jacint@109	78	bool what_heur=1;
jacint@109	79	/*
jacint@109	80	what_heur is 0 in case 'bound decrease'
jacint@109	81	and 1 in case 'highest label'
jacint@109	82	*/
jacint@109	83	bool end=false; //for the 0 case
jacint@109	84	/*
jacint@109	85	Needed for 'bound decrease', 'true'
jacint@109	86	means no active nodes are above bound b.
jacint@109	87	*/
jacint@109	88	int relabel=0;
jacint@109	89	int k=n-2;
jacint@109	90	int b=k;
jacint@109	91	/*
jacint@109	92	b is a bound on the highest level of the stack.
jacint@109	93	k is a bound on the highest nonempty level i < n.
jacint@109	94	*/
jacint@109	95
jacint@109	96	typename Graph::NodeMap<int> level(G,n);
jacint@109	97	typename Graph::NodeMap<T> excess(G);
jacint@109	98
jacint@109	99	std::vector<NodeIt> active(n);
jacint@109	100	typename Graph::NodeMap<NodeIt> next(G);
jacint@109	101	//Stack of the active nodes in level i < n.
jacint@109	102	//We use it in both phases.
jacint@109	103
jacint@109	104	typename Graph::NodeMap<NodeIt> left(G);
jacint@109	105	typename Graph::NodeMap<NodeIt> right(G);
jacint@109	106	std::vector<NodeIt> level_list(n);
jacint@109	107	/*
jacint@109	108	Needed for the list of the nodes in level i.
jacint@109	109	*/
jacint@109	110
jacint@109	111	/Reverse_bfs from t, to find the starting level./
jacint@109	112	level.set(t,0);
jacint@109	113	std::queue<NodeIt> bfs_queue;
jacint@109	114	bfs_queue.push(t);
jacint@109	115
jacint@109	116	while (!bfs_queue.empty()) {
jacint@109	117
jacint@109	118	NodeIt v=bfs_queue.front();
jacint@109	119	bfs_queue.pop();
jacint@109	120	int l=level.get(v)+1;
jacint@109	121
jacint@109	122	for(InEdgeIt e=G.template first<InEdgeIt>(v); e.valid(); ++e) {
jacint@109	123	NodeIt w=G.tail(e);
jacint@109	124	if ( level.get(w) == n && w != s ) {
jacint@109	125	bfs_queue.push(w);
jacint@109	126	NodeIt first=level_list[l];
jacint@109	127	if ( first != 0 ) left.set(first,w);
jacint@109	128	right.set(w,first);
jacint@109	129	level_list[l]=w;
jacint@109	130	level.set(w, l);
jacint@109	131	}
jacint@109	132	}
jacint@109	133	}
jacint@109	134
jacint@109	135	level.set(s,n);
jacint@109	136
jacint@109	137
jacint@109	138	/* Starting flow. It is everywhere 0 at the moment. */
jacint@109	139	for(OutEdgeIt e=G.template first<OutEdgeIt>(s); e.valid(); ++e)
jacint@109	140	{
jacint@109	141	T c=capacity.get(e);
jacint@109	142	if ( c == 0 ) continue;
jacint@109	143	NodeIt w=G.head(e);
jacint@109	144	if ( level.get(w) < n ) {
jacint@109	145	if ( excess.get(w) == 0 && w!=t ) {
jacint@109	146	next.set(w,active[level.get(w)]);
jacint@109	147	active[level.get(w)]=w;
jacint@109	148	}
jacint@109	149	flow.set(e, c);
jacint@109	150	excess.set(w, excess.get(w)+c);
jacint@109	151	}
jacint@109	152	}
jacint@109	153
jacint@109	154	/*
jacint@109	155	End of preprocessing
jacint@109	156	*/
jacint@109	157
jacint@109	158
jacint@109	159
jacint@109	160	/*
jacint@109	161	Push/relabel on the highest level active nodes.
jacint@109	162	*/
jacint@109	163	while ( true ) {
jacint@109	164
jacint@109	165	if ( b == 0 ) {
jacint@109	166	if ( phase ) break;
jacint@109	167
jacint@109	168	if ( !what_heur && !end && k > 0 ) {
jacint@109	169	b=k;
jacint@109	170	end=true;
jacint@109	171	} else {
jacint@109	172	time=currTime();
jacint@109	173	phase=1;
jacint@109	174	level.set(s,0);
jacint@109	175
jacint@109	176	std::queue<NodeIt> bfs_queue;
jacint@109	177	bfs_queue.push(s);
jacint@109	178
jacint@109	179	while (!bfs_queue.empty()) {
jacint@109	180
jacint@109	181	NodeIt v=bfs_queue.front();
jacint@109	182	bfs_queue.pop();
jacint@109	183	int l=level.get(v)+1;
jacint@109	184
jacint@109	185	for(InEdgeIt e=G.template first<InEdgeIt>(v); e.valid(); ++e) {
jacint@109	186	if ( capacity.get(e) == flow.get(e) ) continue;
jacint@109	187	NodeIt u=G.tail(e);
jacint@109	188	if ( level.get(u) >= n ) {
jacint@109	189	bfs_queue.push(u);
jacint@109	190	level.set(u, l);
jacint@109	191	if ( excess.get(u) > 0 ) {
jacint@109	192	next.set(u,active[l]);
jacint@109	193	active[l]=u;
jacint@109	194	}
jacint@109	195	}
jacint@109	196	}
jacint@109	197
jacint@109	198
jacint@109	199	for(OutEdgeIt e=G.template first<OutEdgeIt>(v); e.valid(); ++e) {
jacint@109	200	if ( 0 == flow.get(e) ) continue;
jacint@109	201	NodeIt u=G.head(e);
jacint@109	202	if ( level.get(u) >= n ) {
jacint@109	203	bfs_queue.push(u);
jacint@109	204	level.set(u, l);
jacint@109	205	if ( excess.get(u) > 0 ) {
jacint@109	206	next.set(u,active[l]);
jacint@109	207	active[l]=u;
jacint@109	208	}
jacint@109	209	}
jacint@109	210	}
jacint@109	211	}
jacint@109	212	b=n-2;
jacint@109	213	}
jacint@109	214
jacint@109	215	}
jacint@109	216
jacint@109	217
jacint@109	218	if ( active[b] == 0 ) --b;
jacint@109	219	else {
jacint@109	220	end=false; //needed only for phase 0, case hl2
jacint@109	221
jacint@109	222	NodeIt w=active[b]; //w is a highest label active node.
jacint@109	223	active[b]=next.get(w);
jacint@109	224	int lev=level.get(w);
jacint@109	225	T exc=excess.get(w);
jacint@109	226	int newlevel=n; //In newlevel we bound the next level of w.
jacint@109	227
jacint@109	228	for(OutEdgeIt e=G.template first<OutEdgeIt>(w); e.valid(); ++e) {
jacint@109	229
jacint@109	230	if ( flow.get(e) == capacity.get(e) ) continue;
jacint@109	231	NodeIt v=G.head(e);
jacint@109	232	//e=wv
jacint@109	233
jacint@109	234	if( lev > level.get(v) ) {
jacint@109	235	/Push is allowed now/
jacint@109	236
jacint@109	237	if ( excess.get(v)==0 && v!=t && v!=s ) {
jacint@109	238	int lev_v=level.get(v);
jacint@109	239	next.set(v,active[lev_v]);
jacint@109	240	active[lev_v]=v;
jacint@109	241	}
jacint@109	242	/v becomes active./
jacint@109	243
jacint@109	244	T cap=capacity.get(e);
jacint@109	245	T flo=flow.get(e);
jacint@109	246	T remcap=cap-flo;
jacint@109	247
jacint@109	248	if ( remcap >= exc ) {
jacint@109	249	/A nonsaturating push./
jacint@109	250
jacint@109	251	flow.set(e, flo+exc);
jacint@109	252	excess.set(v, excess.get(v)+exc);
jacint@109	253	exc=0;
jacint@109	254	break;
jacint@109	255
jacint@109	256	} else {
jacint@109	257	/A saturating push./
jacint@109	258
jacint@109	259	flow.set(e, cap);
jacint@109	260	excess.set(v, excess.get(v)+remcap);
jacint@109	261	exc-=remcap;
jacint@109	262	}
jacint@109	263	} else if ( newlevel > level.get(v) ){
jacint@109	264	newlevel = level.get(v);
jacint@109	265	}
jacint@109	266
jacint@109	267	} //for out edges wv
jacint@109	268
jacint@109	269
jacint@109	270	if ( exc > 0 ) {
jacint@109	271	for( InEdgeIt e=G.template first<InEdgeIt>(w); e.valid(); ++e) {
jacint@109	272
jacint@109	273	if( flow.get(e) == 0 ) continue;
jacint@109	274	NodeIt v=G.tail(e);
jacint@109	275	//e=vw
jacint@109	276
jacint@109	277	if( lev > level.get(v) ) {
jacint@109	278	/Push is allowed now/
jacint@109	279
jacint@109	280	if ( excess.get(v)==0 && v!=t && v!=s ) {
jacint@109	281	int lev_v=level.get(v);
jacint@109	282	next.set(v,active[lev_v]);
jacint@109	283	active[lev_v]=v;
jacint@109	284	/v becomes active./
jacint@109	285	}
jacint@109	286
jacint@109	287	T flo=flow.get(e);
jacint@109	288
jacint@109	289	if ( flo >= exc ) {
jacint@109	290	/A nonsaturating push./
jacint@109	291
jacint@109	292	flow.set(e, flo-exc);
jacint@109	293	excess.set(v, excess.get(v)+exc);
jacint@109	294	exc=0;
jacint@109	295	break;
jacint@109	296	} else {
jacint@109	297	/A saturating push./
jacint@109	298
jacint@109	299	excess.set(v, excess.get(v)+flo);
jacint@109	300	exc-=flo;
jacint@109	301	flow.set(e,0);
jacint@109	302	}
jacint@109	303	} else if ( newlevel > level.get(v) ) {
jacint@109	304	newlevel = level.get(v);
jacint@109	305	}
jacint@109	306	} //for in edges vw
jacint@109	307
jacint@109	308	} // if w still has excess after the out edge for cycle
jacint@109	309
jacint@109	310	excess.set(w, exc);
jacint@109	311
jacint@109	312	/*
jacint@109	313	Relabel
jacint@109	314	*/
jacint@109	315
jacint@109	316
jacint@109	317	if ( exc > 0 ) {
jacint@109	318	//now 'lev' is the old level of w
jacint@109	319
jacint@109	320	if ( phase ) {
jacint@109	321	level.set(w,++newlevel);
jacint@109	322	next.set(w,active[newlevel]);
jacint@109	323	active[newlevel]=w;
jacint@109	324	b=newlevel;
jacint@109	325	} else {
jacint@109	326	//unlacing
jacint@109	327	NodeIt right_n=right.get(w);
jacint@109	328	NodeIt left_n=left.get(w);
jacint@109	329
jacint@109	330	if ( right_n != 0 ) {
jacint@109	331	if ( left_n != 0 ) {
jacint@109	332	right.set(left_n, right_n);
jacint@109	333	left.set(right_n, left_n);
jacint@109	334	} else {
jacint@109	335	level_list[lev]=right_n;
jacint@109	336	left.set(right_n, 0);
jacint@109	337	}
jacint@109	338	} else {
jacint@109	339	if ( left_n != 0 ) {
jacint@109	340	right.set(left_n, 0);
jacint@109	341	} else {
jacint@109	342	level_list[lev]=0;
jacint@109	343
jacint@109	344	}
jacint@109	345	}
jacint@109	346
jacint@109	347	if ( level_list[lev]==0 ) {
jacint@109	348
jacint@109	349	for (int i=lev; i!=k ; ) {
jacint@109	350	NodeIt v=level_list[++i];
jacint@109	351	while ( v != 0 ) {
jacint@109	352	level.set(v,n);
jacint@109	353	v=right.get(v);
jacint@109	354	}
jacint@109	355	level_list[i]=0;
jacint@109	356	if ( !what_heur ) active[i]=0;
jacint@109	357	}
jacint@109	358
jacint@109	359	level.set(w,n);
jacint@109	360	b=lev-1;
jacint@109	361	k=b;
jacint@109	362
jacint@109	363	} else {
jacint@109	364
jacint@109	365	if ( newlevel == n ) level.set(w,n);
jacint@109	366	else {
jacint@109	367	level.set(w,++newlevel);
jacint@109	368	next.set(w,active[newlevel]);
jacint@109	369	active[newlevel]=w;
jacint@109	370	if ( what_heur ) b=newlevel;
jacint@109	371	if ( k < newlevel ) ++k;
jacint@109	372	NodeIt first=level_list[newlevel];
jacint@109	373	if ( first != 0 ) left.set(first,w);
jacint@109	374	right.set(w,first);
jacint@109	375	left.set(w,0);
jacint@109	376	level_list[newlevel]=w;
jacint@109	377	}
jacint@109	378	}
jacint@109	379
jacint@109	380
jacint@109	381	++relabel;
jacint@109	382	if ( relabel >= heur ) {
jacint@109	383	relabel=0;
jacint@109	384	if ( what_heur ) {
jacint@109	385	what_heur=0;
jacint@109	386	heur=heur0;
jacint@109	387	end=false;
jacint@109	388	} else {
jacint@109	389	what_heur=1;
jacint@109	390	heur=heur1;
jacint@109	391	b=k;
jacint@109	392	}
jacint@109	393	}
jacint@109	394	} //phase 0
jacint@109	395
jacint@109	396
jacint@109	397	} // if ( exc > 0 )
jacint@109	398
jacint@109	399
jacint@109	400	} // if stack[b] is nonempty
jacint@109	401
jacint@109	402	} // while(true)
jacint@109	403
jacint@109	404
jacint@109	405	value = excess.get(t);
jacint@109	406	/Max flow value./
jacint@109	407
jacint@109	408	} //void run()
jacint@109	409
jacint@109	410
jacint@109	411
jacint@109	412
jacint@109	413
jacint@109	414	/*
jacint@109	415	Returns the maximum value of a flow.
jacint@109	416	*/
jacint@109	417
jacint@109	418	T maxFlow() {
jacint@109	419	return value;
jacint@109	420	}
jacint@109	421
jacint@109	422
jacint@109	423
jacint@109	424	/*
jacint@109	425	For the maximum flow x found by the algorithm,
jacint@109	426	it returns the flow value on edge e, i.e. x(e).
jacint@109	427	*/
jacint@109	428
jacint@109	429	T flowOnEdge(EdgeIt e) {
jacint@109	430	return flow.get(e);
jacint@109	431	}
jacint@109	432
jacint@109	433
jacint@109	434
jacint@109	435	FlowMap Flow() {
jacint@109	436	return flow;
jacint@109	437	}
jacint@109	438
jacint@109	439
jacint@109	440
jacint@109	441	void Flow(FlowMap& _flow ) {
jacint@109	442	for(EachNodeIt v=G.template first<EachNodeIt>() ; v.valid(); ++v)
jacint@109	443	_flow.set(v,flow.get(v));
jacint@109	444	}
jacint@109	445
jacint@109	446
jacint@109	447
jacint@109	448	/*
jacint@109	449	Returns the minimum min cut, by a bfs from s in the residual graph.
jacint@109	450	*/
jacint@109	451
jacint@109	452	template<typename CutMap>
jacint@109	453	void minCut(CutMap& M) {
jacint@109	454
jacint@109	455	std::queue<NodeIt> queue;
jacint@109	456
jacint@109	457	M.set(s,true);
jacint@109	458	queue.push(s);
jacint@109	459
jacint@109	460	while (!queue.empty()) {
jacint@109	461	NodeIt w=queue.front();
jacint@109	462	queue.pop();
jacint@109	463
jacint@109	464	for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
jacint@109	465	NodeIt v=G.head(e);
jacint@109	466	if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
jacint@109	467	queue.push(v);
jacint@109	468	M.set(v, true);
jacint@109	469	}
jacint@109	470	}
jacint@109	471
jacint@109	472	for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
jacint@109	473	NodeIt v=G.tail(e);
jacint@109	474	if (!M.get(v) && flow.get(e) > 0 ) {
jacint@109	475	queue.push(v);
jacint@109	476	M.set(v, true);
jacint@109	477	}
jacint@109	478	}
jacint@109	479
jacint@109	480	}
jacint@109	481
jacint@109	482	}
jacint@109	483
jacint@109	484
jacint@109	485
jacint@109	486	/*
jacint@109	487	Returns the maximum min cut, by a reverse bfs
jacint@109	488	from t in the residual graph.
jacint@109	489	*/
jacint@109	490
jacint@109	491	template<typename CutMap>
jacint@109	492	void maxMinCut(CutMap& M) {
jacint@109	493
jacint@109	494	std::queue<NodeIt> queue;
jacint@109	495
jacint@109	496	M.set(t,true);
jacint@109	497	queue.push(t);
jacint@109	498
jacint@109	499	while (!queue.empty()) {
jacint@109	500	NodeIt w=queue.front();
jacint@109	501	queue.pop();
jacint@109	502
jacint@109	503	for(InEdgeIt e=G.template first<InEdgeIt>(w) ; e.valid(); ++e) {
jacint@109	504	NodeIt v=G.tail(e);
jacint@109	505	if (!M.get(v) && flow.get(e) < capacity.get(e) ) {
jacint@109	506	queue.push(v);
jacint@109	507	M.set(v, true);
jacint@109	508	}
jacint@109	509	}
jacint@109	510
jacint@109	511	for(OutEdgeIt e=G.template first<OutEdgeIt>(w) ; e.valid(); ++e) {
jacint@109	512	NodeIt v=G.head(e);
jacint@109	513	if (!M.get(v) && flow.get(e) > 0 ) {
jacint@109	514	queue.push(v);
jacint@109	515	M.set(v, true);
jacint@109	516	}
jacint@109	517	}
jacint@109	518	}
jacint@109	519
jacint@109	520	for(EachNodeIt v=G.template first<EachNodeIt>() ; v.valid(); ++v) {
jacint@109	521	M.set(v, !M.get(v));
jacint@109	522	}
jacint@109	523
jacint@109	524	}
jacint@109	525
jacint@109	526
jacint@109	527
jacint@109	528	template<typename CutMap>
jacint@109	529	void minMinCut(CutMap& M) {
jacint@109	530	minCut(M);
jacint@109	531	}
jacint@109	532
jacint@109	533
jacint@109	534
jacint@109	535	};
jacint@109	536	}//namespace
jacint@109	537	#endif
jacint@109	538
jacint@109	539
jacint@109	540
jacint@109	541

author	jacint
	Sat, 21 Feb 2004 21:40:59 +0000
changeset 110	3c53698842dd
permissions	-rw-r--r--