Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

findAll(2)
{(2,C), (2,E)}
{(5,A), (7,B), (2,C), (8,D), (2,E)}
size()
5
{(5,A), (7,B), (2,C), (8,D), (2,E)}
remove(find(5))
(5,A)
{(7,B), (2,C), (8,D), (2,E)}
find(5)
null
{(7,B), (2,C), (8,D), (2,E)
9.3.1 List-Based Dictionaries and Audit Trails
A simple way of realizing a dictionary uses an unordered list to store the key-value
entries. Such an implementation is often called a log file or audit trail. The primary
applications of audit trails are situations where we wish to archive structured data.
For example, many operating systems store log files of login requests they process.
The typical scenario is that there are many insertions into the dictionary but few
searches. For example, searching such an operating system log file typically occurs
only after something goes wrong. Thus, a list-based dictionary supports simple and
fast insertions, possibly at the expense of search time, by storing entries of a
dictionary in arbitrary order. (See Figure 9.6.)
Figure 9.6: Realization of a dictionary D by means
of a log file. We show only the keys in this dictionary, so
as to highlight its unordered list implementation.
547