src/lemon/radix_heap.h
author athos
Wed, 23 Mar 2005 11:51:40 +0000
changeset 1247 60708e1475ae
parent 1186 448f76e44b24
child 1331 7e93d3f0406d
permissions -rw-r--r--
Completions.
     1 /* -*- C++ -*-
     2  * src/lemon/bin_heap.h - Part of LEMON, a generic C++ optimization library
     3  *
     4  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     5  * (Egervary Combinatorial Optimization Research Group, EGRES).
     6  *
     7  * Permission to use, modify and distribute this software is granted
     8  * provided that this copyright notice appears in all copies. For
     9  * precise terms see the accompanying LICENSE file.
    10  *
    11  * This software is provided "AS IS" with no warranty of any kind,
    12  * express or implied, and with no claim as to its suitability for any
    13  * purpose.
    14  *
    15  */
    16 
    17 #ifndef LEMON_RADIX_HEAP_H
    18 #define LEMON_RADIX_HEAP_H
    19 
    20 ///\ingroup auxdat
    21 ///\file
    22 ///\brief Radix Heap implementation.
    23 ///\todo It should be documented.
    24 
    25 #include <vector>
    26 #include <lemon/error.h>
    27 
    28 namespace lemon {
    29 
    30   /// \addtogroup auxdat
    31   /// @{
    32 
    33   /// A Radix Heap implementation.
    34   
    35   ///\todo Please document...
    36   ///
    37   ///\sa BinHeap
    38   ///\sa Dijkstra
    39 
    40   class UnderFlowPriorityException : public RuntimeError {
    41   public:
    42     virtual const char* exceptionName() const {
    43       return "lemon::UnderFlowPriorityException";
    44     }  
    45   };
    46 
    47   template <typename _Item, typename _ItemIntMap>
    48   class RadixHeap {
    49 
    50   public:
    51     typedef _Item Item;
    52     // FIXME: stl-ben nem ezt hivjak value_type -nak, hanem a kovetkezot...
    53     typedef int Prio;
    54     typedef _ItemIntMap ItemIntMap;
    55 
    56     /**
    57      * Each Item element have a state associated to it. It may be "in heap",
    58      * "pre heap" or "post heap". The later two are indifferent from the
    59      * heap's point of view, but may be useful to the user.
    60      *
    61      * The ItemIntMap _should_ be initialized in such way, that it maps
    62      * PRE_HEAP (-1) to any element to be put in the heap...
    63      */
    64     ///\todo it is used nowhere
    65     ///
    66     enum state_enum {
    67       IN_HEAP = 0,
    68       PRE_HEAP = -1,
    69       POST_HEAP = -2
    70     };
    71 
    72   private:
    73     
    74     struct RadixItem {
    75       int prev, next, box;
    76       Item item;
    77       int prio;
    78       RadixItem(Item _item, int _prio) : item(_item), prio(_prio) {}
    79     };
    80 
    81     struct RadixBox {
    82       int first;
    83       int min, size;
    84       RadixBox(int _min, int _size) : first(-1), min(_min), size(_size) {}
    85     };
    86 
    87     std::vector<RadixItem> data;
    88     std::vector<RadixBox> boxes;
    89 
    90     ItemIntMap &iim;
    91 
    92 
    93   public:
    94     ///\e
    95     explicit RadixHeap(ItemIntMap &_iim) : iim(_iim) {
    96       boxes.push_back(RadixBox(0, 1));
    97       boxes.push_back(RadixBox(1, 1));
    98     }
    99 
   100     ///\e
   101     RadixHeap(ItemIntMap &_iim, int capacity) : iim(_iim) {
   102       boxes.push_back(RadixBox(0, 1));
   103       boxes.push_back(RadixBox(1, 1));
   104       while (upper(boxes.back(), capacity)) {
   105 	extend();
   106       }
   107     }
   108 
   109     ///\e
   110     int size() const { return data.size(); }
   111     ///\e
   112     bool empty() const { return data.empty(); }
   113 
   114   private:
   115 
   116     bool upper(int box, Prio prio) {
   117       return prio < boxes[box].min;
   118     }
   119 
   120     bool lower(int box, Prio prio) {
   121       return prio >= boxes[box].min + boxes[box].size;
   122     }
   123 
   124     /// \brief Remove item from the box list.
   125     void remove(int index) {
   126       if (data[index].prev >= 0) {
   127 	data[data[index].prev].next = data[index].next;
   128       } else {
   129 	boxes[data[index].box].first = data[index].next;
   130       }
   131       if (data[index].next >= 0) {
   132 	data[data[index].next].prev = data[index].prev;
   133       }
   134     }
   135 
   136     /// \brief Insert item into the box list.
   137     void insert(int box, int index) {
   138       if (boxes[box].first == -1) {
   139 	boxes[box].first = index;
   140 	data[index].next = data[index].prev = -1;
   141       } else {
   142 	data[index].next = boxes[box].first;
   143 	data[boxes[box].first].prev = index;
   144 	data[index].prev = -1;
   145 	boxes[box].first = index;
   146       }
   147       data[index].box = box;
   148     }
   149 
   150     /// \brief Add a new box to the box list.
   151     void extend() {
   152       int min = boxes.back().min + boxes.back().size;
   153       int size = 2 * boxes.back().size;
   154       boxes.push_back(RadixBox(min, size));
   155     }
   156 
   157     /// \brief Move an item up into the proper box.
   158     void bubble_up(int index) {
   159       if (!lower(data[index].box, data[index].prio)) return;
   160       remove(index);
   161       int box = findUp(data[index].box, data[index].prio);
   162       insert(box, index);      
   163     }
   164 
   165     /// \brief Find up the proper box for the item with the given prio.
   166     int findUp(int start, int prio) {
   167       while (lower(start, prio)) {
   168 	if (++start == (int)boxes.size()) {
   169 	  extend();
   170 	}
   171       }
   172       return start;
   173     }
   174 
   175     /// \brief Move an item down into the proper box.
   176     void bubble_down(int index) {
   177       if (!upper(data[index].box, data[index].prio)) return;
   178       remove(index);
   179       int box = findDown(data[index].box, data[index].prio);
   180       insert(box, index);
   181     }
   182 
   183     /// \brief Find up the proper box for the item with the given prio.
   184     int findDown(int start, int prio) {
   185       while (upper(start, prio)) {
   186 	if (--start < 0) throw UnderFlowPriorityException();
   187       }
   188       return start;
   189     }
   190 
   191     /// \brief Find the first not empty box.
   192     int findFirst() {
   193       int first = 0;
   194       while (boxes[first].first == -1) ++first;
   195       return first;
   196     }
   197 
   198     /// \brief Gives back the minimal prio of the box.
   199     int minValue(int box) {
   200       int min = data[boxes[box].first].prio;
   201       for (int k = boxes[box].first; k != -1; k = data[k].next) {
   202 	if (data[k].prio < min) min = data[k].prio;
   203       }
   204       return min;
   205     }
   206 
   207     /// \brief Rearrange the items of the heap and makes the 
   208     /// first box not empty.
   209     void moveDown() {
   210       //      print(); printf("moveDown\n"); fflush(stdout);       
   211       int box = findFirst();
   212       if (box == 0) return;
   213       int min = minValue(box);
   214       for (int i = 0; i <= box; ++i) {
   215 	boxes[i].min = min;
   216 	min += boxes[i].size;
   217       }
   218       int curr = boxes[box].first, next;
   219       while (curr != -1) {
   220 	next = data[curr].next;
   221 	bubble_down(curr);
   222 	curr = next;
   223       }      
   224     }
   225 
   226     void relocate_last(int index) {
   227       if (index != (int)data.size() - 1) {
   228 	data[index] = data.back();
   229 	if (data[index].prev != -1) {
   230 	  data[data[index].prev].next = index;
   231 	} else {
   232 	  boxes[data[index].box].first = index;
   233 	}
   234 	if (data[index].next != -1) {
   235 	  data[data[index].next].prev = index;
   236 	}
   237 	iim[data[index].item] = index;
   238       }
   239       data.pop_back();
   240     }
   241 
   242   public:
   243 
   244     ///\e
   245     void push(const Item &i, const Prio &p) {
   246       fflush(stdout);
   247       int n = data.size();
   248       iim.set(i, n);
   249       data.push_back(RadixItem(i, p));
   250       while (lower(boxes.size() - 1, p)) {
   251 	extend();
   252       }
   253       int box = findDown(boxes.size() - 1, p);
   254       insert(box, n);
   255       //      printf("Push %d\n", p);
   256       //print();
   257     }
   258 
   259     ///\e
   260     Item top() const {
   261       //      print(); printf("top\n");  fflush(stdout);
   262       const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown();
   263       return data[boxes[0].first].item;
   264       //      print(); printf("top_end\n");  fflush(stdout);
   265     }
   266 
   267     /// Returns the prio of the top element of the heap.
   268     Prio prio() const {
   269       //      print(); printf("prio\n"); fflush(stdout);
   270       const_cast<RadixHeap<Item, ItemIntMap>*>(this)->moveDown();
   271       return data[boxes[0].first].prio;
   272      }
   273 
   274     ///\e
   275     void pop() {
   276       //      print(); printf("pop\n"); fflush(stdout);
   277       moveDown();
   278       int index = boxes[0].first;
   279       iim[data[index].item] = POST_HEAP;
   280       remove(index);
   281       relocate_last(index);
   282       //      printf("Pop \n");
   283       //print();
   284     }
   285 
   286     ///\e
   287     void erase(const Item &i) {
   288       int index = iim[i];
   289       iim[i] = POST_HEAP;
   290       remove(index);
   291       relocate_last(index);
   292    }
   293 
   294     ///\e
   295     Prio operator[](const Item &i) const {
   296       int idx = iim[i];
   297       return data[idx].prio;
   298     }
   299 
   300     ///\e
   301     void set(const Item &i, const Prio &p) {
   302       int idx = iim[i];
   303       if( idx < 0 ) {
   304 	push(i, p);
   305       }
   306       else if( p >= data[idx].prio ) {
   307 	data[idx].prio = p;
   308 	bubble_up(idx);
   309       } else {
   310 	data[idx].prio = p;
   311 	bubble_down(idx);
   312       }
   313     }
   314 
   315     ///\e
   316     void decrease(const Item &i, const Prio &p) {
   317       //      print(); printf("decrease\n"); fflush(stdout);
   318       int idx = iim[i];
   319       data[idx].prio = p;
   320       bubble_down(idx);
   321     }
   322 
   323     ///\e
   324     void increase(const Item &i, const Prio &p) {
   325       int idx = iim[i];
   326       data[idx].prio = p;
   327       bubble_up(idx);
   328     }
   329 
   330     ///\e
   331     state_enum state(const Item &i) const {
   332       int s = iim[i];
   333       if( s >= 0 ) s = 0;
   334       return state_enum(s);
   335     }
   336 
   337 //     void print() const {
   338 //       for (int i = 0; i < boxes.size(); ++i) {
   339 // 	printf("(%d, %d) ", boxes[i].min, boxes[i].size);
   340 // 	for (int k = boxes[i].first; k != -1; k = data[k].next) {
   341 // 	  printf("%d ", data[k].prio);
   342 // 	}
   343 // 	printf("\n");
   344 //       }
   345 //       fflush(stdout);
   346 //     }
   347 
   348   }; // class RadixHeap
   349 
   350 
   351   ///@}
   352 
   353 } // namespace lemon
   354 
   355 #endif // LEMON_RADIX_HEAP_H