template<typename PR, typename IM, typename CMP>
class lemon::concepts::Heap< PR, IM, CMP >
This concept class describes the main interface of heaps. The various heap structures are efficient implementations of the abstract data type priority queue. They store items with specified values called priorities in such a way that finding and removing the item with minimum priority are efficient. The basic operations are adding and erasing items, changing the priority of an item, etc.
Heaps are crucial in several algorithms, such as Dijkstra and Prim. Any class that conforms to this concept can be used easily in such algorithms.
- Template Parameters
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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> . |
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| Heap (ItemIntMap &map) |
| Constructor.
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| Heap (ItemIntMap &map, const CMP &comp) |
| Constructor.
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int | size () const |
| The number of items stored in the heap.
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bool | empty () const |
| Check if the heap is empty.
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void | clear () |
| Make the heap empty.
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void | push (const Item &i, const Prio &p) |
| Insert an item into the heap with the given priority.
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Item | top () const |
| Return the item having minimum priority.
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Prio | prio () const |
| The minimum priority.
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void | pop () |
| Remove the item having minimum priority.
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void | erase (const Item &i) |
| Remove the given item from the heap.
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Prio | operator[] (const Item &i) const |
| The priority of the given item.
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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.
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void | decrease (const Item &i, const Prio &p) |
| Decrease the priority of an item to the given value.
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void | increase (const Item &i, const Prio &p) |
| Increase the priority of an item to the given value.
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State | state (const Item &i) const |
| Return the state of an item.
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void | state (const Item &i, State st) |
| Set the state of an item in the heap.
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template<typename PR , typename IM , typename CMP >
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. The "in heap" state constant.
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PRE_HEAP | = -1. The "pre-heap" state constant.
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POST_HEAP | = -2. The "post-heap" state constant.
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template<typename PR , typename IM , typename CMP >
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
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