Design a data structure that supports adding elements and removing all occurrences of a given element, while printing the remaining elements in their original insertion order.
- add(int x): Inserts the element x into the data structure.
- removeAndPrint(int x): Removes all occurrences of x and prints the remaining elements in insertion order.
Example:
Input:
add(10), add(20), add(10), add(30), removeAndPrint(10)
add(30), add(40), add(60), removeAndPrint(30)
Output:
20 30
20 40 60
Using ArrayList vs LinkedList
We can use ArrayList or LinkedList to implement this data structure. Below is a comparison:
ArrayList Approach:
- Add Operation: O(1) (Amortized Time Complexity)
- RemoveAndPrint Operation: O(n) (Since shifting is required after removal)
LinkedList Approach (Preferred Solution):
- Add Operation: O(1) (Worst case as well)
- RemoveAndPrint Operation: O(n) (Efficient with iterators)
Since LinkedList allows fast insertions and removals using iterators, it is an optimal choice.
Approach(using LinkedList)
Follow the below steps:
- Store all elements in a LinkedList to preserve insertion order.
- Insert elements into the list using the add(int x) method.
- Traverse the list using an Iterator to safely remove all occurrences of the given element.
- Print the remaining elements in the same order as they were inserted.
Time Complexity
- add(int x): O(1) -> inserting at the end of a LinkedList.
- removeAndPrint(int x): O(n) -> traverses the list once to remove and print elements.
Space Complexity: O(n) -> extra space used to store n elements in the LinkedList.
