src/work/alpar/dijkstra/bin_heap.hh
author beckerjc
Fri, 26 Mar 2004 13:59:59 +0000
changeset 246 dc95ca4ebc7b
parent 224 5bc1c83257f8
permissions -rw-r--r--
koztes valtozat
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/* FIXME: Copyright ... 
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 *
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 * This implementation is heavily based on STL's heap functions and
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 * the similar class by Alpar Juttner in IKTA...
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 */
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/******
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 *
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 * BinHeap<KeyType, ValueType, KeyIntMap, [ValueCompare]>
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 *
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 * Ez az osztaly kulcs-ertek parok tarolasara alkalmas binaris kupacot
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 * valosit meg.
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 * A kupacban legfolul mindig az a par talalhato, amiben az _ertek_ a
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 * legkisebb. (Gondolj a Dijkstra pont-tavolsag kupacara; igazabol ahhoz
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 * lett keszitve...)
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 *
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 * Megjegyzes: egy kicsit gyanus nekem, hogy a kupacos temakorben nem
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 * azt hivjak kulcsnak, amit most en annak nevezek. :) En olyan 
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 * property_map -os ertelemben hasznalom.
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 *
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 * A hasznalatahoz szukseg van egy irhato/olvashato property_map-re, ami
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 * a kulcsokhoz egy int-et tud tarolni (ezzel tudom megkeresni az illeto
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 * elemet a kupacban a csokkentes es hasonlo muveletekhez).
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 * A map-re csak referenciat tarol, ugy hogy a kupac elete folyan a map-nek
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 * is elnie kell. (???)
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 *
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 * Ketfele modon hasznalhato:
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 * Lusta mod:
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 * put(Key, Value) metodussal pakolunk a kupacba,
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 * aztan o majd eldonti, hogy ez az elem mar benne van-e es ha igen, akkor
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 * csokkentettunk-e rajta, vagy noveltunk.
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 * Ehhez nagyon fontos, hogy az atadott property map inicializalva legyen
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 * minden szobajovo kulcs ertekre, -1 -es ertekkel!
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 * Es ilyen esetben a kulcsokrol lekerdezheto az allapotuk a state metodussal:
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 * (nem jart meg a kupacban PRE_HEAP=-1, epp a kupacban van IN_HEAP=0,
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 *  mar kikerult a kupacbol POST_HEAP=-2).
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 * Szoval ebben a modban a kupac nagyjabol hasznalhato property_map-kent, csak
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 * meg meg tudja mondani a "legkisebb" erteku elemet. De csak nagyjabol,
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 * hiszen a kupacbol kikerult elemeknek elvesz az ertekuk...
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 *
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 * Kozvetlen mod:
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 * push(Key, Value) metodussal belerakunk a kupacba (ha az illeto kulcs mar
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 * benn volt, akkor gaz).
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 * increase/decrease(Key k, Value new_value) metodusokkal lehet
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 * novelni/csokkenteni az illeto kulcshoz tartozo erteket. (Ha nem volt meg
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 * benne a kupacban az illeto kulcs, vagy nem abba az iranyba valtoztattad
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 * az erteket, amerre mondtad -- gaz).
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 *
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 * Termeszetesen a fenti ket modot ertelemszeruen lehet keverni.
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 * Ja es mindig nagyon gaz, ha belepiszkalsz a map-be, amit a kupac
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 * hasznal. :-))
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 *
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 *
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 * Bocs, most faradt vagyok, majd egyszer leforditom. (Misi)
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 *
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 */
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#ifndef BIN_HEAP_HH
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#define BIN_HEAP_HH
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///\file
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///\brief Binary Heap implementation.
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#include <vector>
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#include <utility>
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#include <functional>
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namespace hugo {
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  /// A Binary Heap implementation.
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  template <typename Key, typename Val, typename KeyIntMap,
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	    typename Compare = std::less<Val> >
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  class BinHeap {
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  public:
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    typedef Key	             KeyType;
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    // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
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    typedef Val              ValueType;
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    typedef std::pair<KeyType,ValueType>     PairType;
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    typedef KeyIntMap        KeyIntMapType;
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    typedef Compare          ValueCompare;
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    /**
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     * Each Key element have a state associated to it. It may be "in heap",
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     * "pre heap" or "post heap". The later two are indifferent from the
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     * heap's point of view, but may be useful to the user.
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     *
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     * The KeyIntMap _should_ be initialized in such way, that it maps
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     * PRE_HEAP (-1) to any element to be put in the heap...
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     */
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    ///\todo it is used nowhere
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    ///
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    enum state_enum {
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      IN_HEAP = 0,
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      PRE_HEAP = -1,
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      POST_HEAP = -2
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    };
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  private:
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    std::vector<PairType> data;
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    Compare comp;
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    // FIXME: jo ez igy???
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    KeyIntMap &kim;
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  public:
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    BinHeap(KeyIntMap &_kim) : kim(_kim) {}
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    BinHeap(KeyIntMap &_kim, const Compare &_comp) : comp(_comp), kim(_kim) {}
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    int size() const { return data.size(); }
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    bool empty() const { return data.empty(); }
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  private:
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    static int parent(int i) { return (i-1)/2; }
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    static int second_child(int i) { return 2*i+2; }
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    bool less(const PairType &p1, const PairType &p2) {
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      return comp(p1.second, p2.second);
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    }
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    int bubble_up(int hole, PairType p);
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    int bubble_down(int hole, PairType p, int length);
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    void move(const PairType &p, int i) {
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      data[i] = p;
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      kim.set(p.first, i);
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    }
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    void rmidx(int h) {
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      int n = data.size()-1;
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      if( h>=0 && h<=n ) {
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	kim.set(data[h].first, POST_HEAP);
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	if ( h<n ) {
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	  bubble_down(h, data[n], n);
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	}
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	data.pop_back();
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      }
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    }
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  public:
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    void push(const PairType &p) {
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      int n = data.size();
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      data.resize(n+1);
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      bubble_up(n, p);
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    }
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    void push(const Key &k, const Val &v) { push(PairType(k,v)); }
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    Key top() const {
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      // FIXME: test size>0 ?
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      return data[0].first;
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    }
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    Val topValue() const {
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      // FIXME: test size>0 ?
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      return data[0].second;
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    }
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    void pop() {
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      rmidx(0);
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    }
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    void erase(const Key &k) {
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      rmidx(kim[k]);
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    }
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    Val operator[](const Key &k) const {
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      int idx = kim[k];
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      return data[idx].second;
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    }
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    void put(const Key &k, const Val &v) {
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      int idx = kim[k];
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      if( idx < 0 ) {
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	push(k,v);
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      }
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      else if( comp(v, data[idx].second) ) {
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	bubble_up(idx, PairType(k,v));
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      }
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      else {
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	bubble_down(idx, PairType(k,v), data.size());
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      }
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    }
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    void decrease(const Key &k, const Val &v) {
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      int idx = kim[k];
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      bubble_up(idx, PairType(k,v));
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    }
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    void increase(const Key &k, const Val &v) {
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      int idx = kim[k];
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      bubble_down(idx, PairType(k,v), data.size());
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    }
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    state_enum state(const Key &k) const {
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      int s = kim[k];
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      if( s>=0 )
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	s=0;
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      return state_enum(s);
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    }
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  }; // class BinHeap
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  template <typename K, typename V, typename M, typename C>
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  int BinHeap<K,V,M,C>::bubble_up(int hole, PairType p) {
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    int par = parent(hole);
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    while( hole>0 && less(p,data[par]) ) {
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      move(data[par],hole);
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      hole = par;
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      par = parent(hole);
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    }
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    move(p, hole);
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    return hole;
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  }
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  template <typename K, typename V, typename M, typename C>
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  int BinHeap<K,V,M,C>::bubble_down(int hole, PairType p, int length) {
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    int child = second_child(hole);
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    while(child < length) {
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      if( less(data[child-1], data[child]) ) {
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	--child;
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      }
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      if( !less(data[child], p) )
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	goto ok;
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      move(data[child], hole);
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      hole = child;
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      child = second_child(hole);
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    }
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    child--;
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    if( child<length && less(data[child], p) ) {
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      move(data[child], hole);
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      hole=child;
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    }
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  ok:
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    move(p, hole);
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    return hole;
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  }
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} // namespace hugo
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#endif // BIN_HEAP_HH