What Are the Advantages and Disadvantages of Linked Lists vs Arrays?

Arrays provide fast indexed access and low per-element memory use, while linked lists provide flexible sizing and efficient insertion or deletion once the relevant node is known. The better structure depends on the operations and memory constraints required by the algorithm.

An array stores elements in indexed positions, typically in contiguous memory. Therefore, accessing an element by index takes constant time, $O(1)$. However, inserting or deleting an element in the middle normally requires later elements to be shifted, taking $O(n)$ time.

A linked list consists of nodes, each containing data and a reference to another node. Nodes do not need contiguous memory. Insertion or deletion is $O(1)$ when the target node or its predecessor is already known, because references can be redirected; finding that position still requires sequential traversal and is usually $O(n)$.

For example, repeatedly reading the tenth value suits an array because direct indexing is available. A list of tasks that frequently gains or loses items in different positions may suit a linked list.

A common misconception is that linked-list insertion is always $O(1)$. It is only $O(1)$ after the insertion position has been found; searching for that position may be $O(n)$.

In an IB response, compare both structures against the scenario rather than merely listing features. Justify the choice using access pattern, insertion and deletion frequency, size flexibility, and memory overhead, linking the answer to abstract data type implementation in B4.1.