Chapter 3: Optimal Trees and Branchings - UKP

Optimal Trees and Branchings
Priority queues
A priority queue Q is an abstract data structure managing a set of objects of type T .
Every element in Q has a key of an ordered number type NT (N, Z, ...)
A priority queue supports the following operations:
void create-pq(): create an empty priority queue Q
void insert(T & x, NT y): insert the element x with key value y = key[x] into Q.
T& find-min(): find the element x with the lowest key value and return reference to it.
void delete-min(): remove the element with smallest key value from Q.
void decrease-key(T x, NT y): decrease the key value of x to the new value Wert y.
(Precondition: key[x] > y)
bool empty(): returns TRUE if Q is empty.
Annotation: Analogously, the data structure might deliver the element with the largest key value.
Efficient Graph Algorithms | Wolfgang Stille | WS 2011/2012 | Chapter III - Optimal Trees and Branchings | 33