diff -r c35afa9e89e7 -r ef88c0a30f85 lemon/bucket_heap.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lemon/bucket_heap.h	Thu Nov 05 15:48:01 2009 +0100
@@ -0,0 +1,594 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2009
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_BUCKET_HEAP_H
+#define LEMON_BUCKET_HEAP_H
+
+///\ingroup heaps
+///\file
+///\brief Bucket heap implementation.
+
+#include <vector>
+#include <utility>
+#include <functional>
+
+namespace lemon {
+
+  namespace _bucket_heap_bits {
+
+    template <bool MIN>
+    struct DirectionTraits {
+      static bool less(int left, int right) {
+        return left < right;
+      }
+      static void increase(int& value) {
+        ++value;
+      }
+    };
+
+    template <>
+    struct DirectionTraits<false> {
+      static bool less(int left, int right) {
+        return left > right;
+      }
+      static void increase(int& value) {
+        --value;
+      }
+    };
+
+  }
+
+  /// \ingroup heaps
+  ///
+  /// \brief Bucket heap data structure.
+  ///
+  /// This class implements the \e bucket \e heap data structure.
+  /// It practically conforms to the \ref concepts::Heap "heap concept",
+  /// but it has some limitations.
+  ///
+  /// The bucket heap is a very simple structure. It can store only
+  /// \c int priorities and it maintains a list of items for each priority
+  /// in the range <tt>[0..C)</tt>. So it should only be used when the
+  /// priorities are small. It is not intended to use as a Dijkstra heap.
+  ///
+  /// \tparam IM A read-writable item map with \c int values, used
+  /// internally to handle the cross references.
+  /// \tparam MIN Indicate if the heap is a \e min-heap or a \e max-heap.
+  /// The default is \e min-heap. If this parameter is set to \c false,
+  /// then the comparison is reversed, so the top(), prio() and pop()
+  /// functions deal with the item having maximum priority instead of the
+  /// minimum.
+  ///
+  /// \sa SimpleBucketHeap
+  template <typename IM, bool MIN = true>
+  class BucketHeap {
+
+  public:
+
+    /// Type of the item-int map.
+    typedef IM ItemIntMap;
+    /// Type of the priorities.
+    typedef int Prio;
+    /// Type of the items stored in the heap.
+    typedef typename ItemIntMap::Key Item;
+    /// Type of the item-priority pairs.
+    typedef std::pair<Item,Prio> Pair;
+
+  private:
+
+    typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
+
+  public:
+
+    /// \brief Type to represent the states of the items.
+    ///
+    /// Each item has a state associated to it. It can be "in heap",
+    /// "pre-heap" or "post-heap". The latter two are indifferent from the
+    /// heap's point of view, but may be useful to the user.
+    ///
+    /// The item-int map must be initialized in such way that it assigns
+    /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
+    enum State {
+      IN_HEAP = 0,    ///< = 0.
+      PRE_HEAP = -1,  ///< = -1.
+      POST_HEAP = -2  ///< = -2.
+    };
+
+  public:
+
+    /// \brief Constructor.
+    ///
+    /// Constructor.
+    /// \param map A map that assigns \c int values to the items.
+    /// It is used internally to handle the cross references.
+    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
+    explicit BucketHeap(ItemIntMap &map) : _iim(map), _minimum(0) {}
+
+    /// \brief The number of items stored in the heap.
+    ///
+    /// This function returns the number of items stored in the heap.
+    int size() const { return _data.size(); }
+
+    /// \brief Check if the heap is empty.
+    ///
+    /// This function returns \c true if the heap is empty.
+    bool empty() const { return _data.empty(); }
+
+    /// \brief Make the heap empty.
+    ///
+    /// This functon makes the heap empty.
+    /// It does not change the cross reference map. If you want to reuse
+    /// a heap that is not surely empty, you should first clear it and
+    /// then you should set the cross reference map to \c PRE_HEAP
+    /// for each item.
+    void clear() {
+      _data.clear(); _first.clear(); _minimum = 0;
+    }
+
+  private:
+
+    void relocateLast(int idx) {
+      if (idx + 1 < int(_data.size())) {
+        _data[idx] = _data.back();
+        if (_data[idx].prev != -1) {
+          _data[_data[idx].prev].next = idx;
+        } else {
+          _first[_data[idx].value] = idx;
+        }
+        if (_data[idx].next != -1) {
+          _data[_data[idx].next].prev = idx;
+        }
+        _iim[_data[idx].item] = idx;
+      }
+      _data.pop_back();
+    }
+
+    void unlace(int idx) {
+      if (_data[idx].prev != -1) {
+        _data[_data[idx].prev].next = _data[idx].next;
+      } else {
+        _first[_data[idx].value] = _data[idx].next;
+      }
+      if (_data[idx].next != -1) {
+        _data[_data[idx].next].prev = _data[idx].prev;
+      }
+    }
+
+    void lace(int idx) {
+      if (int(_first.size()) <= _data[idx].value) {
+        _first.resize(_data[idx].value + 1, -1);
+      }
+      _data[idx].next = _first[_data[idx].value];
+      if (_data[idx].next != -1) {
+        _data[_data[idx].next].prev = idx;
+      }
+      _first[_data[idx].value] = idx;
+      _data[idx].prev = -1;
+    }
+
+  public:
+
+    /// \brief Insert a pair of item and priority into the heap.
+    ///
+    /// This function inserts \c p.first to the heap with priority
+    /// \c p.second.
+    /// \param p The pair to insert.
+    /// \pre \c p.first must not be stored in the heap.
+    void push(const Pair& p) {
+      push(p.first, p.second);
+    }
+
+    /// \brief Insert an item into the heap with the given priority.
+    ///
+    /// This function inserts the given item into the heap with the
+    /// given priority.
+    /// \param i The item to insert.
+    /// \param p The priority of the item.
+    /// \pre \e i must not be stored in the heap.
+    void push(const Item &i, const Prio &p) {
+      int idx = _data.size();
+      _iim[i] = idx;
+      _data.push_back(BucketItem(i, p));
+      lace(idx);
+      if (Direction::less(p, _minimum)) {
+        _minimum = p;
+      }
+    }
+
+    /// \brief Return the item having minimum priority.
+    ///
+    /// This function returns the item having minimum priority.
+    /// \pre The heap must be non-empty.
+    Item top() const {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      return _data[_first[_minimum]].item;
+    }
+
+    /// \brief The minimum priority.
+    ///
+    /// This function returns the minimum priority.
+    /// \pre The heap must be non-empty.
+    Prio prio() const {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      return _minimum;
+    }
+
+    /// \brief Remove the item having minimum priority.
+    ///
+    /// This function removes the item having minimum priority.
+    /// \pre The heap must be non-empty.
+    void pop() {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      int idx = _first[_minimum];
+      _iim[_data[idx].item] = -2;
+      unlace(idx);
+      relocateLast(idx);
+    }
+
+    /// \brief Remove the given item from the heap.
+    ///
+    /// This function removes the given item from the heap if it is
+    /// already stored.
+    /// \param i The item to delete.
+    /// \pre \e i must be in the heap.
+    void erase(const Item &i) {
+      int idx = _iim[i];
+      _iim[_data[idx].item] = -2;
+      unlace(idx);
+      relocateLast(idx);
+    }
+
+    /// \brief The priority of the given item.
+    ///
+    /// This function returns the priority of the given item.
+    /// \param i The item.
+    /// \pre \e i must be in the heap.
+    Prio operator[](const Item &i) const {
+      int idx = _iim[i];
+      return _data[idx].value;
+    }
+
+    /// \brief Set the priority of an item or insert it, if it is
+    /// not stored in the heap.
+    ///
+    /// This method sets the priority of the given item if it is
+    /// already stored in the heap. Otherwise it inserts the given
+    /// item into the heap with the given priority.
+    /// \param i The item.
+    /// \param p The priority.
+    void set(const Item &i, const Prio &p) {
+      int idx = _iim[i];
+      if (idx < 0) {
+        push(i, p);
+      } else if (Direction::less(p, _data[idx].value)) {
+        decrease(i, p);
+      } else {
+        increase(i, p);
+      }
+    }
+
+    /// \brief Decrease the priority of an item to the given value.
+    ///
+    /// This function decreases the priority of an item to the given value.
+    /// \param i The item.
+    /// \param p The priority.
+    /// \pre \e i must be stored in the heap with priority at least \e p.
+    void decrease(const Item &i, const Prio &p) {
+      int idx = _iim[i];
+      unlace(idx);
+      _data[idx].value = p;
+      if (Direction::less(p, _minimum)) {
+        _minimum = p;
+      }
+      lace(idx);
+    }
+
+    /// \brief Increase the priority of an item to the given value.
+    ///
+    /// This function increases the priority of an item to the given value.
+    /// \param i The item.
+    /// \param p The priority.
+    /// \pre \e i must be stored in the heap with priority at most \e p.
+    void increase(const Item &i, const Prio &p) {
+      int idx = _iim[i];
+      unlace(idx);
+      _data[idx].value = p;
+      lace(idx);
+    }
+
+    /// \brief Return the state of an item.
+    ///
+    /// This method returns \c PRE_HEAP if the given item has never
+    /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
+    /// and \c POST_HEAP otherwise.
+    /// In the latter case it is possible that the item will get back
+    /// to the heap again.
+    /// \param i The item.
+    State state(const Item &i) const {
+      int idx = _iim[i];
+      if (idx >= 0) idx = 0;
+      return State(idx);
+    }
+
+    /// \brief Set the state of an item in the heap.
+    ///
+    /// This function sets the state of the given item in the heap.
+    /// It can be used to manually clear the heap when it is important
+    /// to achive better time complexity.
+    /// \param i The item.
+    /// \param st The state. It should not be \c IN_HEAP.
+    void state(const Item& i, State st) {
+      switch (st) {
+      case POST_HEAP:
+      case PRE_HEAP:
+        if (state(i) == IN_HEAP) {
+          erase(i);
+        }
+        _iim[i] = st;
+        break;
+      case IN_HEAP:
+        break;
+      }
+    }
+
+  private:
+
+    struct BucketItem {
+      BucketItem(const Item& _item, int _value)
+        : item(_item), value(_value) {}
+
+      Item item;
+      int value;
+
+      int prev, next;
+    };
+
+    ItemIntMap& _iim;
+    std::vector<int> _first;
+    std::vector<BucketItem> _data;
+    mutable int _minimum;
+
+  }; // class BucketHeap
+
+  /// \ingroup heaps
+  ///
+  /// \brief Simplified bucket heap data structure.
+  ///
+  /// This class implements a simplified \e bucket \e heap data
+  /// structure. It does not provide some functionality, but it is
+  /// faster and simpler than BucketHeap. The main difference is
+  /// that BucketHeap stores a doubly-linked list for each key while
+  /// this class stores only simply-linked lists. It supports erasing
+  /// only for the item having minimum priority and it does not support
+  /// key increasing and decreasing.
+  ///
+  /// Note that this implementation does not conform to the
+  /// \ref concepts::Heap "heap concept" due to the lack of some 
+  /// functionality.
+  ///
+  /// \tparam IM A read-writable item map with \c int values, used
+  /// internally to handle the cross references.
+  /// \tparam MIN Indicate if the heap is a \e min-heap or a \e max-heap.
+  /// The default is \e min-heap. If this parameter is set to \c false,
+  /// then the comparison is reversed, so the top(), prio() and pop()
+  /// functions deal with the item having maximum priority instead of the
+  /// minimum.
+  ///
+  /// \sa BucketHeap
+  template <typename IM, bool MIN = true >
+  class SimpleBucketHeap {
+
+  public:
+
+    /// Type of the item-int map.
+    typedef IM ItemIntMap;
+    /// Type of the priorities.
+    typedef int Prio;
+    /// Type of the items stored in the heap.
+    typedef typename ItemIntMap::Key Item;
+    /// Type of the item-priority pairs.
+    typedef std::pair<Item,Prio> Pair;
+
+  private:
+
+    typedef _bucket_heap_bits::DirectionTraits<MIN> Direction;
+
+  public:
+
+    /// \brief Type to represent the states of the items.
+    ///
+    /// Each item has a state associated to it. It can be "in heap",
+    /// "pre-heap" or "post-heap". The latter two are indifferent from the
+    /// heap's point of view, but may be useful to the user.
+    ///
+    /// The item-int map must be initialized in such way that it assigns
+    /// \c PRE_HEAP (<tt>-1</tt>) to any element to be put in the heap.
+    enum State {
+      IN_HEAP = 0,    ///< = 0.
+      PRE_HEAP = -1,  ///< = -1.
+      POST_HEAP = -2  ///< = -2.
+    };
+
+  public:
+
+    /// \brief Constructor.
+    ///
+    /// Constructor.
+    /// \param map A map that assigns \c int values to the items.
+    /// It is used internally to handle the cross references.
+    /// The assigned value must be \c PRE_HEAP (<tt>-1</tt>) for each item.
+    explicit SimpleBucketHeap(ItemIntMap &map)
+      : _iim(map), _free(-1), _num(0), _minimum(0) {}
+
+    /// \brief The number of items stored in the heap.
+    ///
+    /// This function returns the number of items stored in the heap.
+    int size() const { return _num; }
+
+    /// \brief Check if the heap is empty.
+    ///
+    /// This function returns \c true if the heap is empty.
+    bool empty() const { return _num == 0; }
+
+    /// \brief Make the heap empty.
+    ///
+    /// This functon makes the heap empty.
+    /// It does not change the cross reference map. If you want to reuse
+    /// a heap that is not surely empty, you should first clear it and
+    /// then you should set the cross reference map to \c PRE_HEAP
+    /// for each item.
+    void clear() {
+      _data.clear(); _first.clear(); _free = -1; _num = 0; _minimum = 0;
+    }
+
+    /// \brief Insert a pair of item and priority into the heap.
+    ///
+    /// This function inserts \c p.first to the heap with priority
+    /// \c p.second.
+    /// \param p The pair to insert.
+    /// \pre \c p.first must not be stored in the heap.
+    void push(const Pair& p) {
+      push(p.first, p.second);
+    }
+
+    /// \brief Insert an item into the heap with the given priority.
+    ///
+    /// This function inserts the given item into the heap with the
+    /// given priority.
+    /// \param i The item to insert.
+    /// \param p The priority of the item.
+    /// \pre \e i must not be stored in the heap.
+    void push(const Item &i, const Prio &p) {
+      int idx;
+      if (_free == -1) {
+        idx = _data.size();
+        _data.push_back(BucketItem(i));
+      } else {
+        idx = _free;
+        _free = _data[idx].next;
+        _data[idx].item = i;
+      }
+      _iim[i] = idx;
+      if (p >= int(_first.size())) _first.resize(p + 1, -1);
+      _data[idx].next = _first[p];
+      _first[p] = idx;
+      if (Direction::less(p, _minimum)) {
+        _minimum = p;
+      }
+      ++_num;
+    }
+
+    /// \brief Return the item having minimum priority.
+    ///
+    /// This function returns the item having minimum priority.
+    /// \pre The heap must be non-empty.
+    Item top() const {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      return _data[_first[_minimum]].item;
+    }
+
+    /// \brief The minimum priority.
+    ///
+    /// This function returns the minimum priority.
+    /// \pre The heap must be non-empty.
+    Prio prio() const {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      return _minimum;
+    }
+
+    /// \brief Remove the item having minimum priority.
+    ///
+    /// This function removes the item having minimum priority.
+    /// \pre The heap must be non-empty.
+    void pop() {
+      while (_first[_minimum] == -1) {
+        Direction::increase(_minimum);
+      }
+      int idx = _first[_minimum];
+      _iim[_data[idx].item] = -2;
+      _first[_minimum] = _data[idx].next;
+      _data[idx].next = _free;
+      _free = idx;
+      --_num;
+    }
+
+    /// \brief The priority of the given item.
+    ///
+    /// This function returns the priority of the given item.
+    /// \param i The item.
+    /// \pre \e i must be in the heap.
+    /// \warning This operator is not a constant time function because
+    /// it scans the whole data structure to find the proper value.
+    Prio operator[](const Item &i) const {
+      for (int k = 0; k < int(_first.size()); ++k) {
+        int idx = _first[k];
+        while (idx != -1) {
+          if (_data[idx].item == i) {
+            return k;
+          }
+          idx = _data[idx].next;
+        }
+      }
+      return -1;
+    }
+
+    /// \brief Return the state of an item.
+    ///
+    /// This method returns \c PRE_HEAP if the given item has never
+    /// been in the heap, \c IN_HEAP if it is in the heap at the moment,
+    /// and \c POST_HEAP otherwise.
+    /// In the latter case it is possible that the item will get back
+    /// to the heap again.
+    /// \param i The item.
+    State state(const Item &i) const {
+      int idx = _iim[i];
+      if (idx >= 0) idx = 0;
+      return State(idx);
+    }
+
+  private:
+
+    struct BucketItem {
+      BucketItem(const Item& _item)
+        : item(_item) {}
+
+      Item item;
+      int next;
+    };
+
+    ItemIntMap& _iim;
+    std::vector<int> _first;
+    std::vector<BucketItem> _data;
+    int _free, _num;
+    mutable int _minimum;
+
+  }; // class SimpleBucketHeap
+
+}
+
+#endif