A Practical Introduction to Data Structures and Algorithm Analysis

140 Chap. 4 Lists, Stacks, and Queues/** The Dictionary abstract class. */public interface Dictionary {/** Reinitialize dictionary */public void clear();/** Insert a record@param k The key for the record being inserted.@param e The record being inserted. */public void insert(Key k, E e);/** Remove and return a record.@param k The key of the record to be removed.@return A maching record. If multiple records match"k", remove an arbitrary one. Return null if no recordwith key "k" exists. */public E remove(Key k);/** Remove and return an arbitrary record from dictionary.@return the record removed, or null if none exists. */public E removeAny();/** @return A record matching "k" (null if none exists).If multiple records match, return an arbitrary one.@param k The key of the record to find */public E find(Key k);/** @return the number of records in the dictionary. */public int size();};Figure 4.27 The ADT for a simple dictionary.records in sorted order in an array, which permits a binary search. Fortunately, inpractice most fields of most records consist of simple data types with natural totalorders. For example, integers, floats, doubles, and character strings all are totallyordered. Ordering fields that are naturally multi-dimensional, such as a point in twoor three dimensions, present special opportunities if we wish to take advantage oftheir multidimensional nature. This problem is addressed in Section 13.3.Figure 4.27 shows the definition for a simple abstract dictionary class. Themethods insert and find are the heart of the class. Method insert takes arecord and inserts it into the dictionary. Method find takes a key value and returnssome record from the dictionary whose key matches the one provided. If there aremultiple records in the dictionary with that key value, there is no requirement as towhich one is returned.