Linked Implementation of OrderedSet
We want to efficiently implement the OrderedSet ADT with an underlying linked list.
Exercise Complete the following table.
| Operation | How? | Runtime |
|---|---|---|
has | ||
insert | ||
remove | ||
size |
Solution
Except for size, all operations require a helper find method to check if an element exists. Thus, we cannot do better than Linear Search for find. (Performing Binary Search on a linked list is futile as its cost is $O(n)$ while its implementation is more complex than Linear Search.)
| Operation | How? | Runtime |
|---|---|---|
has | return find(t) != null; | $O(n)$ |
insert | Find where to insert, then insert! | $O(n)$ |
remove | remove(find(t)); | $O(n)$ |
size | return numElements; | $O(1)$ |
find | Linear search | $O(n)$ |
We can come up with a clever implementation so the find method would return the previous node of the target (instead of the target itself). This will make the insert method easier to use the same find operation like the one used by other operations. However, we leave this as an (unsolved) exercise to you to implement the functions of OrderedSet using a linked list.