[Lemon-commits] [lemon_svn] deba: r2756 - hugo/trunk/lemon
Lemon SVN
svn at lemon.cs.elte.hu
Mon Nov 6 20:54:59 CET 2006
Author: deba
Date: Wed May 17 11:07:24 2006
New Revision: 2756
Modified:
hugo/trunk/lemon/bucket_heap.h
Log:
SimpleBucketHeap added
It does not supports erasing, decreasing, increasing.
It contains single linked lists
It can be used to store levels for push-relabel algorithms
Modified: hugo/trunk/lemon/bucket_heap.h
==============================================================================
--- hugo/trunk/lemon/bucket_heap.h (original)
+++ hugo/trunk/lemon/bucket_heap.h Wed May 17 11:07:24 2006
@@ -30,7 +30,7 @@
namespace lemon {
/// \ingroup auxdat
-
+ ///
/// \brief A Bucket Heap implementation.
///
/// This class implements the \e bucket \e heap data structure. A \e heap
@@ -241,7 +241,7 @@
}
/// \brief Decreases the priority of \c i to \c p.
-
+ ///
/// This method decreases the priority of item \c i to \c p.
/// \pre \c i must be stored in the heap with priority at least \c
/// p relative to \c Compare.
@@ -512,6 +512,303 @@
}; // class BucketHeap
+ /// \ingroup auxdat
+ ///
+ /// \brief A Simplified Bucket Heap implementation.
+ ///
+ /// This class implements a simplified \e bucket \e heap data
+ /// structure. It does not provide some functionality but it faster
+ /// and simplier data structure than the BucketHeap. The main
+ /// difference is that the BucketHeap stores for every key a double
+ /// linked list while this class stores just simple lists. In the
+ /// other way it does not supports erasing each elements just the
+ /// minimal and it does not supports key increasing, decreasing.
+ ///
+ /// \param _Item Type of the items to be stored.
+ /// \param _ItemIntMap A read and writable Item int map, used internally
+ /// to handle the cross references.
+ /// \param minimize If the given parameter is true then the heap gives back
+ /// the lowest priority.
+ ///
+ /// \sa BucketHeap
+ template <typename _Item, typename _ItemIntMap, bool minimize = true >
+ class SimpleBucketHeap {
+
+ public:
+ typedef _Item Item;
+ typedef int Prio;
+ typedef std::pair<Item, Prio> Pair;
+ typedef _ItemIntMap ItemIntMap;
+
+ /// \brief Type to represent the items states.
+ ///
+ /// Each Item element have a state associated to it. It may 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 ItemIntMap \e should be initialized in such way that it maps
+ /// PRE_HEAP (-1) to any element to be put in the heap...
+ enum state_enum {
+ IN_HEAP = 0,
+ PRE_HEAP = -1,
+ POST_HEAP = -2
+ };
+
+ public:
+
+ /// \brief The constructor.
+ ///
+ /// The constructor.
+ /// \param _index should be given to the constructor, since it is used
+ /// internally to handle the cross references. The value of the map
+ /// should be PRE_HEAP (-1) for each element.
+ explicit SimpleBucketHeap(ItemIntMap &_index)
+ : index(_index), free(-1), num(0), minimal(0) {}
+
+ /// \brief Returns the number of items stored in the heap.
+ ///
+ /// The number of items stored in the heap.
+ int size() const { return num; }
+
+ /// \brief Checks if the heap stores no items.
+ ///
+ /// Returns \c true if and only if the heap stores no items.
+ bool empty() const { return num == 0; }
+
+ /// \brief Make empty this heap.
+ ///
+ /// Make empty this heap. It does not change the cross reference
+ /// map. If you want to reuse a heap what is not surely empty you
+ /// should first clear the heap and after that you should set the
+ /// cross reference map for each item to \c PRE_HEAP.
+ void clear() {
+ data.clear(); first.clear(); free = -1; num = 0; minimal = 0;
+ }
+
+ /// \brief Insert a pair of item and priority into the heap.
+ ///
+ /// Adds \c p.first to the heap with priority \c p.second.
+ /// \param p The pair to insert.
+ void push(const Pair& p) {
+ push(p.first, p.second);
+ }
+
+ /// \brief Insert an item into the heap with the given priority.
+ ///
+ /// Adds \c i to the heap with priority \c p.
+ /// \param i The item to insert.
+ /// \param p The priority of the item.
+ void push(const Item &i, const Prio &p) {
+ int idx;
+ if (free == -1) {
+ idx = data.size();
+ data.push_back(BucketItem(i, p));
+ } else {
+ idx = free;
+ free = data[idx].next;
+ data[idx].item = i; data[idx].value = p;
+ }
+ index[i] = idx;
+ if (p >= (int)first.size()) first.resize(p + 1, -1);
+ data[idx].next = first[p];
+ first[p] = idx;
+ if (p < minimal) {
+ minimal = p;
+ }
+ ++num;
+ }
+
+ /// \brief Returns the item with minimum priority.
+ ///
+ /// This method returns the item with minimum priority.
+ /// \pre The heap must be nonempty.
+ Item top() const {
+ while (first[minimal] == -1) {
+ ++minimal;
+ }
+ return data[first[minimal]].item;
+ }
+
+ /// \brief Returns the minimum priority.
+ ///
+ /// It returns the minimum priority.
+ /// \pre The heap must be nonempty.
+ Prio prio() const {
+ while (first[minimal] == -1) {
+ ++minimal;
+ }
+ return minimal;
+ }
+
+ /// \brief Deletes the item with minimum priority.
+ ///
+ /// This method deletes the item with minimum priority from the heap.
+ /// \pre The heap must be non-empty.
+ void pop() {
+ while (first[minimal] == -1) {
+ ++minimal;
+ }
+ int idx = first[minimal];
+ index[data[idx].item] = -2;
+ first[minimal] = data[idx].next;
+ data[idx].next = free;
+ free = idx;
+ --num;
+ }
+
+ /// \brief Returns the priority of \c i.
+ ///
+ /// This function returns the priority of item \c i.
+ /// \pre \c i must be in the heap.
+ /// \param i The item.
+ Prio operator[](const Item &i) const {
+ int idx = index[i];
+ return data[idx].value;
+ }
+
+ /// \brief Returns if \c item is in, has already been in, or has
+ /// never been in the heap.
+ ///
+ /// This method returns PRE_HEAP if \c item has never been in the
+ /// heap, IN_HEAP if it is in the heap at the moment, and POST_HEAP
+ /// otherwise. In the latter case it is possible that \c item will
+ /// get back to the heap again.
+ /// \param i The item.
+ state_enum state(const Item &i) const {
+ int idx = index[i];
+ if (idx >= 0) idx = 0;
+ return state_enum(idx);
+ }
+
+ private:
+
+ struct BucketItem {
+ BucketItem(const Item& _item, int _value)
+ : item(_item), value(_value) {}
+
+ Item item;
+ int value;
+
+ int next;
+ };
+
+ ItemIntMap& index;
+ std::vector<int> first;
+ std::vector<BucketItem> data;
+ int free, num;
+ mutable int minimal;
+
+ }; // class SimpleBucketHeap
+
+ template <typename _Item, typename _ItemIntMap>
+ class SimpleBucketHeap<_Item, _ItemIntMap, false> {
+
+ public:
+ typedef _Item Item;
+ typedef int Prio;
+ typedef std::pair<Item, Prio> Pair;
+ typedef _ItemIntMap ItemIntMap;
+
+ enum state_enum {
+ IN_HEAP = 0,
+ PRE_HEAP = -1,
+ POST_HEAP = -2
+ };
+
+ public:
+
+ explicit SimpleBucketHeap(ItemIntMap &_index)
+ : index(_index), free(-1), num(0), maximal(0) {}
+
+ int size() const { return num; }
+
+ bool empty() const { return num == 0; }
+
+ void clear() {
+ data.clear(); first.clear(); free = -1; num = 0; maximal = 0;
+ }
+
+ void push(const Pair& p) {
+ push(p.first, p.second);
+ }
+
+ void push(const Item &i, const Prio &p) {
+ int idx;
+ if (free == -1) {
+ idx = data.size();
+ data.push_back(BucketItem(i, p));
+ } else {
+ idx = free;
+ free = data[idx].next;
+ data[idx].item = i; data[idx].value = p;
+ }
+ index[i] = idx;
+ if (p >= (int)first.size()) first.resize(p + 1, -1);
+ data[idx].next = first[p];
+ first[p] = idx;
+ if (p > maximal) {
+ maximal = p;
+ }
+ ++num;
+ }
+
+ Item top() const {
+ while (first[maximal] == -1) {
+ --maximal;
+ }
+ return data[first[maximal]].item;
+ }
+
+ Prio prio() const {
+ while (first[maximal] == -1) {
+ --maximal;
+ }
+ return maximal;
+ }
+
+ void pop() {
+ while (first[maximal] == -1) {
+ --maximal;
+ }
+ int idx = first[maximal];
+ index[data[idx].item] = -2;
+ first[maximal] = data[idx].next;
+ data[idx].next = free;
+ free = idx;
+ --num;
+ }
+
+ Prio operator[](const Item &i) const {
+ int idx = index[i];
+ return data[idx].value;
+ }
+
+ state_enum state(const Item &i) const {
+ int idx = index[i];
+ if (idx >= 0) idx = 0;
+ return state_enum(idx);
+ }
+
+ private:
+
+ struct BucketItem {
+ BucketItem(const Item& _item, int _value)
+ : item(_item), value(_value) {}
+
+ Item item;
+ int value;
+
+ int next;
+ };
+
+ ItemIntMap& index;
+ std::vector<int> first;
+ std::vector<BucketItem> data;
+ int free, num;
+ mutable int maximal;
+
+ };
+
}
#endif
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