What is the difference between hash table and stack?

The main difference between a hash table and a stack is their underlying data structure and the way they store and retrieve data.

A hash table, also known as a hash map, is a data structure that uses a hash function to map keys to values. It typically provides constant-time average case complexity for insertion, deletion, and retrieval operations. Hash tables allow for efficient lookup and storage of data based on a key-value pair.

On the other hand, a stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. It allows for the insertion and removal of elements only at one end, known as the top of the stack. The operations performed on a stack are push (inserting an element onto the top) and pop (removing the topmost element). Stacks are commonly used in programming for managing function calls, recursion, and expression evaluation.

In summary, the key differences between a hash table and a stack are:
1. Data Structure: Hash tables use a hash function to map keys to values, while stacks are based on a linear structure.
2. Operations: Hash tables support efficient lookup, insertion, and deletion of key-value pairs, whereas stacks primarily support push and pop operations.
3. Access Pattern: Hash tables allow for random access to data based on keys, while stacks only allow access to the topmost element.
4. Principle: Hash tables do not follow a specific principle for data retrieval, while stacks follow the LIFO principle.