Linked Lists vs. Arrays

Let's put the two data structures against each other to find out which is more efficient.

Array vs. Linked List

Memory Allocation

The main difference between a linked list and an array is the way they are allocated memory. Arrays instantiate a whole block of memory, e.g., array[1000] gets space to store 1000 elements at the start even if it doesn’t contain any element yet. On the other hand, a linked list only instantiates the portion of memory it uses.

Insertion and Deletion

For lists and arrays, many differences can be observed in the way elements are inserted and deleted. In a linked list, insertion and deletion at head happen in a constant amount of time (O(1)), while arrays take O(n) time to insert or delete a value because you have to shift the array elements left or right after that operation.


In an array, it takes constant time to access an index. In a linked list, you have to iterate the list from the start until you find the node with the correct value.

The table given below will summarize the performance difference between linked lists and arrays.

Operation Linked List Array
Insert (at head)
Delete (at head)
Insert (at tail) O(n) O(n)
Delete (at tail) O(n) O(n)

As you can see, there is a trade-off between the facilities provided by both structures.

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