Data Structures and Algorithms
with Object-Oriented Design Patterns in C#|
The separately chained hash table described in the preceding section is essentially a linked-list implementation. We have seen both linked-list and array-based implementations for all of the data structures considered so far and hash tables are no exception. Array-based hash tables are called scatter tables .
The essential idea behind a scatter table is that all of the information is stored within a fixed size array. Hashing is used to identify the position where an item should be stored. When a collision occurs, the colliding item is stored somewhere else in the array.
One of the motivations for using scatter tables can be seen by considering again the linked-list hash table shown in Figure . Since most of the linked lists are empty, much of the array is unused. At the same time, for each item that is added to the table, dynamic memory is consumed. Why not simply store the data in the unused array positions?