Which is better linked list or array?
Last Updated :
18 Mar, 2024
Linked lists and arrays have their own strengths and weaknesses. The choice between them depends on the specific requirements of the task at hand. Arrays are better when you need fast access to elements, while linked lists are better when you need to perform frequent insertions and deletions.
What is an Array?
An array is a data structure that stores elements of the same type in a contiguous block of memory. It is simple and provides fast access to elements based on their index.
Pros of Arrays:
- Fast Access: Jump straight to any item using its index.
- Memory Efficient: No extra space needed for pointers.
Cons of Arrays:
- Fixed Size: You need to know how big your array should be beforehand.
- Insertion and Deletion: Adding or removing items can be slow because other items need to be shifted around.
What is a Linked List?
A linked list, on the other hand, is a linear data structure where each element points to the next. It is more flexible than an array as it allows efficient insertions and deletions.
Pros of Linked Lists:
- Dynamic Size: Grow or shrink the list as needed.
- Easy Insertion/Deletion: Just change the pointers without shifting other elements.
Cons of Linked Lists:
- Slower Access: You have to start at the beginning and follow the links to find an item.
- More Memory: Each element requires extra space for the pointer(s).
Quick Comparison: Linked Lists versus Arrays
Question 1: Which is faster for accessing elements?
Answer: Array - because elements are stored in contiguous memory locations.
Question 2: Which is better for adding or removing elements?
Answer: Linked List - because you don’t need to shift elements after insertion or deletion.
Question 3: Which uses more memory?
Answer: Linked List - because it stores pointers to the next (and previous, in doubly linked lists) elements.
Question 4: Which is better for memory allocation?
Answer: Linked List - because it allocates memory dynamically and can grow as needed.
Question 5: Which is better for large datasets?
Answer: Array - because it can be more time-efficient with bulk operations and better cache locality.
Question 6: Which is better for data of unknown size?
Answer: Linked List - because it doesn’t require you to define the size beforehand.
Question 7: Which is better for sequential access?
Answer: Array - because elements are stored contiguously, making sequential access faster.
Question 8: Which is better for random access?
Answer: Array - because you can jump directly to any element using its index.
Key Difference Between Linked list and Array:
Let's look at the key difference between linked list and Array, which will help us get better understanding which of them we should use.
| Aspect | Linked List | Array |
|---|
| Memory Allocation | Dynamic memory allocation, each node is allocated separately, allowing for flexible memory usage | Static memory allocation, all elements are allocated in contiguous memory locations |
|---|
| Access Time | Access time is O(n), as you need to traverse the list from the head to reach a specific element | Access time is O(1) for accessing elements by index |
|---|
| Insertion/Deletion Time | O(1) for insertion/deletion at the beginning or end of the list, O(n) for insertion/deletion in the middle | O(n) for insertion/deletion in the middle (shifting elements), O(1) for insertion/deletion at the end |
|---|
| Memory Overhead | Additional memory overhead for storing pointers/references to the next node | Minimal memory overhead, as elements are stored in contiguous memory locations |
|---|
| Dynamic Resizing | No need for resizing, as memory allocation is dynamic | May require resizing (reallocating memory) when the array reaches capacity, which can be an expensive operation |
|---|
| Cache Friendliness | Poor cache locality due to scattered memory access, impacting performance | Good cache locality due to contiguous memory allocation, leading to better performance |
|---|
| Usage | Suitable for applications requiring frequent insertion/deletion or where memory usage is unpredictable | Suitable for applications requiring fast random access or when memory usage is known upfront |
|---|
| Implementation | More complex implementation due to the need for handling pointers/references | Relatively simpler implementation |
|---|
| Examples | Singly linked list, doubly linked list, circular linked list | Static arrays, dynamic arrays (e.g., std::vector in C++), matrices |
|---|
Conclusion
It really depends on what you need to do. If you need fast access to elements and you know how many items you have, an array is the way to go. But if you’re going to be adding and removing items a lot, and you’re not sure how many items you’ll end up with, a linked list will make your life easier. Think about your needs, and choose the one that fits best!
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