Detailed Description
template<typename IM>
class lemon::RadixHeap< IM >
This class implements the radix heap data structure. It practically conforms to the heap concept, but it has some limitations due its special implementation. The type of the priorities must be int
and the priority of an item cannot be decreased under the priority of the last removed item.
- Template Parameters:
-
| IM | A read-writable item map with int values, used internally to handle the cross references. |
#include <lemon/radix_heap.h>
List of all members.
Classes |
class | PriorityUnderflowError |
| Exception thrown by RadixHeap. More...
|
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 int | Prio |
| Type of the priorities.
|
typedef ItemIntMap::Key | Item |
| Type of the items stored in the heap.
|
Public Member Functions |
| RadixHeap (ItemIntMap &map, int minimum=0, int capacity=0) |
| Constructor.
|
int | size () const |
| The number of items stored in the heap.
|
bool | empty () const |
| Check if the heap is empty.
|
void | clear (int minimum=0, int capacity=0) |
| Make the heap empty.
|
void | push (const Item &i, const Prio &p) |
| Insert an item into the heap with the given priority.
|
Item | top () const |
| Return the item having minimum priority.
|
Prio | prio () const |
| The minimum priority.
|
void | pop () |
| Remove the item having minimum priority.
|
void | erase (const Item &i) |
| Remove the given item from the heap.
|
Prio | operator[] (const Item &i) const |
| The priority of the given item.
|
void | set (const Item &i, const Prio &p) |
| Set the priority of an item or insert it, if it is not stored in the heap.
|
void | decrease (const Item &i, const Prio &p) |
| Decrease the priority of an item to the given value.
|
void | increase (const Item &i, const Prio &p) |
| Increase the priority of an item to the given value.
|
State | state (const Item &i) const |
| Return the state of an item.
|
void | state (const Item &i, State st) |
| Set the state of an item in the heap.
|
Member Enumeration Documentation
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:
IN_HEAP |
= 0.
|
PRE_HEAP |
= -1.
|
POST_HEAP |
= -2.
|
Constructor & Destructor Documentation
Constructor.
- Parameters:
-
| 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. |
| minimum | The initial minimum value of the heap. |
| capacity | The initial capacity of the heap. |
Member Function Documentation
int size |
( |
|
) |
const [inline] |
This function returns the number of items stored in the heap.
bool empty |
( |
|
) |
const [inline] |
This function returns true
if the heap is empty.
void clear |
( |
int |
minimum = 0 , |
|
|
int |
capacity = 0 | |
|
) |
| | [inline] |
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.
- Parameters:
-
| minimum | The minimum value of the heap. |
| capacity | The capacity of the heap. |
void push |
( |
const Item & |
i, |
|
|
const Prio & |
p | |
|
) |
| | [inline] |
This function inserts the given item into the heap with the given priority.
- Parameters:
-
| i | The item to insert. |
| p | The priority of the item. |
- Precondition:
- i must not be stored in the heap.
- Warning:
- This method may throw an
UnderFlowPriorityException
.
Item top |
( |
|
) |
const [inline] |
This function returns the item having minimum priority.
- Precondition:
- The heap must be non-empty.
Prio prio |
( |
|
) |
const [inline] |
This function returns the minimum priority.
- Precondition:
- The heap must be non-empty.
This function removes the item having minimum priority.
- Precondition:
- The heap must be non-empty.
void erase |
( |
const Item & |
i |
) |
[inline] |
This function removes the given item from the heap if it is already stored.
- Parameters:
-
- Precondition:
- i must be in the heap.
Prio operator[] |
( |
const Item & |
i |
) |
const [inline] |
This function returns the priority of the given item.
- Parameters:
-
- Precondition:
- i must be in the heap.
void set |
( |
const Item & |
i, |
|
|
const Prio & |
p | |
|
) |
| | [inline] |
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.
- Parameters:
-
| i | The item. |
| p | The priority. |
- Precondition:
- i must be in the heap.
- Warning:
- This method may throw an
UnderFlowPriorityException
.
void decrease |
( |
const Item & |
i, |
|
|
const Prio & |
p | |
|
) |
| | [inline] |
This function decreases the priority of an item to the given value.
- Parameters:
-
| i | The item. |
| p | The priority. |
- Precondition:
- i must be stored in the heap with priority at least p.
- Warning:
- This method may throw an
UnderFlowPriorityException
.
void increase |
( |
const Item & |
i, |
|
|
const Prio & |
p | |
|
) |
| | [inline] |
This function increases the priority of an item to the given value.
- Parameters:
-
| i | The item. |
| p | The priority. |
- Precondition:
- i must be stored in the heap with priority at most p.
State state |
( |
const Item & |
i |
) |
const [inline] |
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.
- Parameters:
-
void state |
( |
const Item & |
i, |
|
|
State |
st | |
|
) |
| | [inline] |
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.
- Parameters:
-
| i | The item. |
| st | The state. It should not be IN_HEAP . |