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bin_heap.h

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00001 /* -*- C++ -*-
00002  * lemon/bin_heap.h - Part of LEMON, a generic C++ optimization library
00003  *
00004  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
00005  * (Egervary Research Group on Combinatorial Optimization, EGRES).
00006  *
00007  * Permission to use, modify and distribute this software is granted
00008  * provided that this copyright notice appears in all copies. For
00009  * precise terms see the accompanying LICENSE file.
00010  *
00011  * This software is provided "AS IS" with no warranty of any kind,
00012  * express or implied, and with no claim as to its suitability for any
00013  * purpose.
00014  *
00015  */
00016 
00017 #ifndef LEMON_BIN_HEAP_H
00018 #define LEMON_BIN_HEAP_H
00019 
00023 
00024 #include <vector>
00025 #include <utility>
00026 #include <functional>
00027 
00028 namespace lemon {
00029 
00032 
00034   
00050   template <typename Item, typename Prio, typename ItemIntMap,
00051             typename Compare = std::less<Prio> >
00052   class BinHeap {
00053 
00054   public:
00055     typedef Item                             ItemType;
00056     // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
00057     typedef Prio                             PrioType;
00058     typedef std::pair<ItemType,PrioType>     PairType;
00059     typedef ItemIntMap                       ItemIntMapType;
00060     typedef Compare                          PrioCompare;
00061 
00070     enum state_enum {
00071       IN_HEAP = 0,
00072       PRE_HEAP = -1,
00073       POST_HEAP = -2
00074     };
00075 
00076   private:
00077     std::vector<PairType> data;
00078     Compare comp;
00079     ItemIntMap &iim;
00080 
00081   public:
00088     explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
00089     
00098     BinHeap(ItemIntMap &_iim, const Compare &_comp) 
00099       : iim(_iim), comp(_comp) {}
00100 
00101 
00105     int size() const { return data.size(); }
00106     
00110     bool empty() const { return data.empty(); }
00111 
00112   private:
00113     static int parent(int i) { return (i-1)/2; }
00114     static int second_child(int i) { return 2*i+2; }
00115     bool less(const PairType &p1, const PairType &p2) const {
00116       return comp(p1.second, p2.second);
00117     }
00118 
00119     int bubble_up(int hole, PairType p);
00120     int bubble_down(int hole, PairType p, int length);
00121 
00122     void move(const PairType &p, int i) {
00123       data[i] = p;
00124       iim.set(p.first, i);
00125     }
00126 
00127     void rmidx(int h) {
00128       int n = data.size()-1;
00129       if( h>=0 && h<=n ) {
00130         iim.set(data[h].first, POST_HEAP);
00131         if ( h<n ) {
00132           bubble_down(h, data[n], n);
00133         }
00134         data.pop_back();
00135       }
00136     }
00137 
00138   public:
00143     void push(const PairType &p) {
00144       int n = data.size();
00145       data.resize(n+1);
00146       bubble_up(n, p);
00147     }
00148 
00154     void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
00155 
00161     Item top() const {
00162       return data[0].first;
00163     }
00164 
00169     Prio prio() const {
00170       return data[0].second;
00171     }
00172 
00178     void pop() {
00179       rmidx(0);
00180     }
00181 
00187     void erase(const Item &i) {
00188       rmidx(iim[i]);
00189     }
00190 
00191     
00197     Prio operator[](const Item &i) const {
00198       int idx = iim[i];
00199       return data[idx].second;
00200     }
00201 
00209     void set(const Item &i, const Prio &p) {
00210       int idx = iim[i];
00211       if( idx < 0 ) {
00212         push(i,p);
00213       }
00214       else if( comp(p, data[idx].second) ) {
00215         bubble_up(idx, PairType(i,p));
00216       }
00217       else {
00218         bubble_down(idx, PairType(i,p), data.size());
00219       }
00220     }
00221 
00223 
00229     void decrease(const Item &i, const Prio &p) {
00230       int idx = iim[i];
00231       bubble_up(idx, PairType(i,p));
00232     }
00233     
00241     void increase(const Item &i, const Prio &p) {
00242       int idx = iim[i];
00243       bubble_down(idx, PairType(i,p), data.size());
00244     }
00245 
00254     state_enum state(const Item &i) const {
00255       int s = iim[i];
00256       if( s>=0 )
00257         s=0;
00258       return state_enum(s);
00259     }
00260 
00261   }; // class BinHeap
00262 
00263   
00264   template <typename K, typename V, typename M, typename C>
00265   int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
00266     int par = parent(hole);
00267     while( hole>0 && less(p,data[par]) ) {
00268       move(data[par],hole);
00269       hole = par;
00270       par = parent(hole);
00271     }
00272     move(p, hole);
00273     return hole;
00274   }
00275 
00276   template <typename K, typename V, typename M, typename C>
00277   int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
00278     int child = second_child(hole);
00279     while(child < length) {
00280       if( less(data[child-1], data[child]) ) {
00281         --child;
00282       }
00283       if( !less(data[child], p) )
00284         goto ok;
00285       move(data[child], hole);
00286       hole = child;
00287       child = second_child(hole);
00288     }
00289     child--;
00290     if( child<length && less(data[child], p) ) {
00291       move(data[child], hole);
00292       hole=child;
00293     }
00294   ok:
00295     move(p, hole);
00296     return hole;
00297   }
00298 
00300 
00301 } // namespace lemon
00302 
00303 #endif // LEMON_BIN_HEAP_H

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