This class implements the pairing heap data structure. It fully conforms to the heap concept.
The methods increase() and erase() are not efficient in a pairing heap. In case of many calls of these operations, it is better to use other heap structure, e.g. binary heap.
PR | Type of the priorities of the items. |
IM | A read-writable item map with int values, used internally to handle the cross references. |
CMP | A functor class for comparing the priorities. The default is std::less<PR> . |
#include <lemon/pairing_heap.h>
Public Types | |
enum | State { IN_HEAP = 0, PRE_HEAP = -1, POST_HEAP = -2 } |
Type to represent the states of the items. More... | |
typedef IM | ItemIntMap |
Type of the item-int map. | |
typedef PR | Prio |
Type of the priorities. | |
typedef ItemIntMap::Key | Item |
Type of the items stored in the heap. | |
typedef CMP | Compare |
Functor type for comparing the priorities. | |
Public Member Functions | |
PairingHeap (ItemIntMap &map) | |
Constructor. More... | |
PairingHeap (ItemIntMap &map, const Compare &comp) | |
Constructor. More... | |
int | size () const |
The number of items stored in the heap. More... | |
bool | empty () const |
Check if the heap is empty. More... | |
void | clear () |
Make the heap empty. More... | |
void | set (const Item &item, const Prio &value) |
Set the priority of an item or insert it, if it is not stored in the heap. More... | |
void | push (const Item &item, const Prio &value) |
Insert an item into the heap with the given priority. More... | |
Item | top () const |
Return the item having minimum priority. More... | |
const Prio & | prio () const |
The minimum priority. More... | |
const Prio & | operator[] (const Item &item) const |
The priority of the given item. More... | |
void | pop () |
Remove the item having minimum priority. More... | |
void | erase (const Item &item) |
Remove the given item from the heap. More... | |
void | decrease (Item item, const Prio &value) |
Decrease the priority of an item to the given value. More... | |
void | increase (Item item, const Prio &value) |
Increase the priority of an item to the given value. More... | |
State | state (const Item &item) const |
Return the state of an item. More... | |
void | state (const Item &i, State st) |
Set the state of an item in the heap. More... | |
enum State |
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 PRE_HEAP
(-1
) to any element to be put in the heap.
Enumerator | |
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IN_HEAP |
= 0. |
PRE_HEAP |
= -1. |
POST_HEAP |
= -2. |
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inlineexplicit |
Constructor.
map | A map that assigns int values to the items. It is used internally to handle the cross references. The assigned value must be PRE_HEAP (-1 ) for each item. |
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Constructor.
map | A map that assigns int values to the items. It is used internally to handle the cross references. The assigned value must be PRE_HEAP (-1 ) for each item. |
comp | The function object used for comparing the priorities. |
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This function returns the number of items stored in the heap.
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This function returns true
if the heap is empty.
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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 PRE_HEAP
for each item.
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.
item | The item. |
value | The priority. |
This function inserts the given item into the heap with the given priority.
item | The item to insert. |
value | The priority of the item. |
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This function returns the item having minimum priority.
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This function returns the minimum priority.
This function returns the priority of the given item.
item | The item. |
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This function removes the item having minimum priority.
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inline |
This function removes the given item from the heap if it is already stored.
item | The item to delete. |
This function decreases the priority of an item to the given value.
item | The item. |
value | The priority. |
This function increases the priority of an item to the given value.
item | The item. |
value | The priority. |
This method returns PRE_HEAP
if the given 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 the item will get back to the heap again.
item | The item. |