What is the difference between a linked list and an array?

A linked list and an array are both data structures used to store and organize data, but they have several key differences.

1. Memory Allocation: In an array, elements are stored in contiguous memory locations, meaning that each element is placed right next to the previous one in memory. On the other hand, a linked list does not require contiguous memory allocation. Each element, known as a node, contains a reference to the next node in the list, forming a chain-like structure.

2. Size: Arrays have a fixed size, which is determined at the time of declaration. Once the size is defined, it cannot be changed. In contrast, linked lists can dynamically grow or shrink in size as elements are added or removed.

3. Insertion and Deletion: Insertion and deletion operations in an array can be costly, especially when performed in the middle or beginning of the array. This is because all the elements after the insertion or deletion point need to be shifted accordingly. In a linked list, insertion and deletion operations are generally more efficient since they only require updating the references of adjacent nodes.

4. Access Time: Arrays provide constant-time access to elements based on their index. This means that accessing an element in an array takes the same amount of time, regardless of its position. In contrast, linked lists require traversing the list from the beginning to reach a specific element, resulting in a linear access time.

5. Memory Efficiency: Linked lists are more memory-efficient than arrays in certain scenarios. In an array, memory is allocated for the maximum number of elements, even if they are not all used. In a linked list, memory is allocated only for the elements that are actually present in the list.

6. Flexibility: Arrays are suitable for scenarios where random access to elements is required, such as searching or sorting algorithms. Linked lists, on the other hand, are more flexible when it comes to dynamic data structures, as they can easily accommodate changes in size and structure.

In summary, the main differences between a linked list and an array lie in their memory allocation, size flexibility, efficiency of insertion and deletion operations, access time, memory efficiency, and suitability for different scenarios.