Version 5.0 The LEDA User Manual

11.20 Node Priority Queues ( node pq )
1. Definition
An instance Q of the parameterized data type node pq is a partial function from the
nodes of a graph G to a linearly ordered type P of priorities. The priority of a node is
sometimes called the information of the node. For every graph G only one node pq
may be used and every node of G may be contained in the queue at most once (cf. section
8.1 for general priority queues).
#include < LEDA/graph/node pq.h >
2. Creation
node pq Q(const graph t& G);
creates an instance Q ot type node pq for the nodes of graph G
with dom(Q) = ∅.
3. Operations
void Q.insert(node v, const P & x)
adds the node v with priority x to Q.
Precondition: v ∉ dom(Q).
const P & Q.prio(node v) returns the priority of node v.
Precondition: v ∈ dom(Q).
bool Q.member(node v) returns true if v in Q, false otherwise.
void Q.decrease p(node v, const P & x)
makes x the new priority of node v.
Precondition: x ≤ Q.prio(v).
node Q.find min( ) returns a node with minimal priority (nil if Q is empty).
void Q.del(node v) removes the node v from Q.
node Q.del min( ) removes a node with minimal priority from Q and returns
it (nil if Q is empty).
node Q.del min(P & x) as above, in addition the priority of the removed node
is assigned to x.
void Q.clear( ) makes Q the empty node priority queue.
int Q.size( ) returns |dom(Q)|.
int Q.empty( ) returns true if Q is the empty node priority queue, false
otherwise.