Version 5.0 The LEDA User Manual

11.16 Sets of Nodes ( node set )
1. Definition
An instance S of the data type node set is a subset of the nodes of a graph G. S is said
to be valid for the nodes of G.
#include < LEDA/graph/node set.h >
2. Creation
node set
S(const graph& G);
creates an instance S of type node set valid for all nodes currently
contained in graph G and initializes it to the empty set.
3. Operations
void S.insert(node x) adds node x to S.
void S.del(node x) removes node x from S.
bool S.member(node x) returns true if x in S, false otherwise.
node S.choose( ) returns a node of S.
int S.size( ) returns the size of S.
bool S.empty( ) returns true iff S is the empty set.
void S.clear( ) makes S the empty set.
4. Implementation
A node set S for a graph G is implemented by a combination of a list L of nodes and a
node array of list items associating with each node its position in L. All operations take
constant time, except for clear which takes time O(S). The space requirement is O(n),
where n is the number of nodes of G.