src/lemon/bin_heap.h
changeset 1275 16980bf77bd3
parent 1191 c988f12c6c0c
child 1331 7e93d3f0406d
equal deleted inserted replaced
4:a3b9d4212c2d 5:452dcf21a330
    18 #define LEMON_BIN_HEAP_H
    18 #define LEMON_BIN_HEAP_H
    19 
    19 
    20 ///\ingroup auxdat
    20 ///\ingroup auxdat
    21 ///\file
    21 ///\file
    22 ///\brief Binary Heap implementation.
    22 ///\brief Binary Heap implementation.
    23 ///\todo It should be documented.
       
    24 
    23 
    25 #include <vector>
    24 #include <vector>
    26 #include <utility>
    25 #include <utility>
    27 #include <functional>
    26 #include <functional>
    28 
    27 
    29 namespace lemon {
    28 namespace lemon {
    30 
    29 
    31   /// \addtogroup auxdat
    30   /// \addtogroup auxdat
    32   /// @{
    31   /// @{
    33 
    32 
    34    /// A Binary Heap implementation.
    33   /// A Binary Heap implementation.
    35   
    34   
    36   ///\todo Please document...
    35   ///This class implements the \e binary \e heap data structure. A \e heap
       
    36   ///is a data structure for storing items with specified values called \e
       
    37   ///priorities in such a way that finding the item with minimum priority is
       
    38   ///efficient. \c Compare specifies the ordering of the priorities. In a heap
       
    39   ///one can change the priority of an item, add or erase an item, etc.
       
    40   ///
       
    41   ///\param Item Type of the items to be stored.  
       
    42   ///\param Prio Type of the priority of the items.
       
    43   ///\param ItemIntMap A read and writable Item int map, used internally
       
    44   ///to handle the cross references.
       
    45   ///\param Compare A class for the ordering of the priorities. The
       
    46   ///default is \c std::less<Prio>.
    37   ///
    47   ///
    38   ///\sa FibHeap
    48   ///\sa FibHeap
    39   ///\sa Dijkstra
    49   ///\sa Dijkstra
    40   template <typename Item, typename Prio, typename ItemIntMap,
    50   template <typename Item, typename Prio, typename ItemIntMap,
    41 	    typename Compare = std::less<Prio> >
    51 	    typename Compare = std::less<Prio> >
    70     Compare comp;
    80     Compare comp;
    71     // FIXME: jo ez igy???
    81     // FIXME: jo ez igy???
    72     ItemIntMap &iim;
    82     ItemIntMap &iim;
    73 
    83 
    74   public:
    84   public:
    75     ///\e
    85     ///The constructor
       
    86 
       
    87     /**
       
    88        \c _iim should be given to the constructor, since it is used
       
    89        internally to handle the cross references.
       
    90     */
    76     explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
    91     explicit BinHeap(ItemIntMap &_iim) : iim(_iim) {}
    77     ///\e
    92     
       
    93     ///The constructor
       
    94 
       
    95     /**
       
    96        \c _iim should be given to the constructor, since it is used
       
    97        internally to handle the cross references. \c _comp is an
       
    98        object for ordering of the priorities.
       
    99     */
    78     BinHeap(ItemIntMap &_iim, const Compare &_comp) 
   100     BinHeap(ItemIntMap &_iim, const Compare &_comp) 
    79       : iim(_iim), comp(_comp) {}
   101       : iim(_iim), comp(_comp) {}
    80 
   102 
    81 
   103 
    82     ///\e
   104     ///The number of items stored in the heap.
       
   105 
       
   106     /**
       
   107        Returns the number of items stored in the heap.
       
   108     */
    83     int size() const { return data.size(); }
   109     int size() const { return data.size(); }
    84     ///\e
   110     
       
   111     ///Checks if the heap stores no items.
       
   112     
       
   113     /**
       
   114        Returns \c true if and only if the heap stores no items.
       
   115     */
    85     bool empty() const { return data.empty(); }
   116     bool empty() const { return data.empty(); }
    86 
   117 
    87   private:
   118   private:
    88     static int parent(int i) { return (i-1)/2; }
   119     static int parent(int i) { return (i-1)/2; }
    89     static int second_child(int i) { return 2*i+2; }
   120     static int second_child(int i) { return 2*i+2; }
   109 	data.pop_back();
   140 	data.pop_back();
   110       }
   141       }
   111     }
   142     }
   112 
   143 
   113   public:
   144   public:
   114     ///\e
   145     ///Adds \c p.first to the heap with priority \c p.second.
       
   146     
       
   147     /**
       
   148        Adds \c p.first to the heap with priority \c p.second.
       
   149        \c p.first must not be stored in the heap. 
       
   150     */
   115     void push(const PairType &p) {
   151     void push(const PairType &p) {
   116       int n = data.size();
   152       int n = data.size();
   117       data.resize(n+1);
   153       data.resize(n+1);
   118       bubble_up(n, p);
   154       bubble_up(n, p);
   119     }
   155     }
   120     ///\e
   156 
       
   157     ///Adds \c i to the heap with priority \c p. 
       
   158     
       
   159     /**
       
   160        Adds \c i to the heap with priority \c p. 
       
   161        \pre \c i must not be stored in the heap. 
       
   162     */
   121     void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
   163     void push(const Item &i, const Prio &p) { push(PairType(i,p)); }
   122 
   164 
   123     ///\e
   165     ///Returns the item with minimum priority relative to \c Compare.
       
   166     
       
   167     /**
       
   168        This method returns the item with minimum priority relative to \c
       
   169        Compare.  
       
   170        \pre The heap must be nonempty.  
       
   171     */
   124     Item top() const {
   172     Item top() const {
   125       return data[0].first;
   173       return data[0].first;
   126     }
   174     }
   127     /// Returns the prio of the top element of the heap.
   175 
       
   176     ///Returns the minimum priority relative to \c Compare.
       
   177 
       
   178     /**
       
   179        It returns the minimum priority relative to \c Compare.
       
   180        \pre The heap must be nonempty.
       
   181     */
   128     Prio prio() const {
   182     Prio prio() const {
   129       return data[0].second;
   183       return data[0].second;
   130     }
   184     }
   131 
   185 
   132     ///\e
   186     ///Deletes the item with minimum priority relative to \c Compare.
       
   187 
       
   188     /**
       
   189     This method deletes the item with minimum priority relative to \c
       
   190     Compare from the heap.  
       
   191     \pre The heap must be non-empty.  
       
   192     */
   133     void pop() {
   193     void pop() {
   134       rmidx(0);
   194       rmidx(0);
   135     }
   195     }
   136 
   196 
   137     ///\e
   197     ///Deletes \c i from the heap.
       
   198 
       
   199     /**
       
   200        This method deletes item \c i from the heap, if \c i was
       
   201        already stored in the heap. 
       
   202     */
   138     void erase(const Item &i) {
   203     void erase(const Item &i) {
   139       rmidx(iim[i]);
   204       rmidx(iim[i]);
   140     }
   205     }
   141 
   206 
   142     ///\e
   207     
       
   208     ///Returns the priority of \c i.
       
   209 
       
   210     /**
       
   211        This function returns the priority of item \c i.  
       
   212        \pre \c i must be in the heap.
       
   213     */
   143     Prio operator[](const Item &i) const {
   214     Prio operator[](const Item &i) const {
   144       int idx = iim[i];
   215       int idx = iim[i];
   145       return data[idx].second;
   216       return data[idx].second;
   146     }
   217     }
   147 
   218 
   148     ///\e
   219     ///\c i gets to the heap with priority \c p independently if \c i was already there.
       
   220 
       
   221     /**
       
   222        This method calls \ref push(\c i, \c p) if \c i is not stored
       
   223        in the heap and sets the priority of \c i to \c p otherwise.
       
   224     */
   149     void set(const Item &i, const Prio &p) {
   225     void set(const Item &i, const Prio &p) {
   150       int idx = iim[i];
   226       int idx = iim[i];
   151       if( idx < 0 ) {
   227       if( idx < 0 ) {
   152 	push(i,p);
   228 	push(i,p);
   153       }
   229       }
   157       else {
   233       else {
   158 	bubble_down(idx, PairType(i,p), data.size());
   234 	bubble_down(idx, PairType(i,p), data.size());
   159       }
   235       }
   160     }
   236     }
   161 
   237 
   162     ///\e
   238     ///Decreases the priority of \c i to \c p.
       
   239 
       
   240     /**
       
   241        This method decreases the priority of item \c i to \c p.
       
   242        \pre \c i must be stored in the heap with priority at least \c
       
   243        p relative to \c Compare.
       
   244     */
   163     void decrease(const Item &i, const Prio &p) {
   245     void decrease(const Item &i, const Prio &p) {
   164       int idx = iim[i];
   246       int idx = iim[i];
   165       bubble_up(idx, PairType(i,p));
   247       bubble_up(idx, PairType(i,p));
   166     }
   248     }
   167     ///\e
   249     
       
   250     ///Increases the priority of \c i to \c p.
       
   251 
       
   252     /**
       
   253        This method sets the priority of item \c i to \c p. 
       
   254        \pre \c i must be stored in the heap with priority at most \c
       
   255        p relative to \c Compare.
       
   256     */
   168     void increase(const Item &i, const Prio &p) {
   257     void increase(const Item &i, const Prio &p) {
   169       int idx = iim[i];
   258       int idx = iim[i];
   170       bubble_down(idx, PairType(i,p), data.size());
   259       bubble_down(idx, PairType(i,p), data.size());
   171     }
   260     }
   172 
   261 
   173     ///\e
   262     ///Returns if \c item is in, has already been in, or has never been in the heap.
       
   263 
       
   264     /**
       
   265        This method returns PRE_HEAP if \c item has never been in the
       
   266        heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
       
   267        otherwise. In the latter case it is possible that \c item will
       
   268        get back to the heap again.
       
   269     */
   174     state_enum state(const Item &i) const {
   270     state_enum state(const Item &i) const {
   175       int s = iim[i];
   271       int s = iim[i];
   176       if( s>=0 )
   272       if( s>=0 )
   177 	s=0;
   273 	s=0;
   178       return state_enum(s);
   274       return state_enum(s);