Stack And Queue frequently Asked Questions by expert members with experience in Stack and queue. These questions and answers will help you strengthen your technical skills, prepare for the new job test and quickly revise the concepts

## 6 Stack And Queue Questions and Answers:

### 1 :: Can you please explain stack operation?

Stack is a data structure that follows Last in First out strategy.

Stack Operations:-

Push – Pushes (inserts) the element in the stack. The location is specified by the pointer.
Pop – Pulls (removes) the element out of the stack. The location is specified by the pointer
Swap: - the two top most elements of the stack can be swapped
Peek: - Returns the top element on the stack but does not remove it from the stack
Rotate:- the topmost (n) items can be moved on the stack in a rotating fashion

A stack has a fixed location in the memory. When a data element is pushed in the stack, the pointer points to the current element.

### 2 :: Can you explain queue operation?

Queue is a data structure that follows First in First out strategy.

Queue Operations:

Push – Inserts the element in the queue at the end.
Pop – removes the element out of the queue from the front
Size – Returns the size of the queue
Front – Returns the first element of the queue.
Empty – to find if the queue is empty.

### 3 :: Tell me how to implement queue using stack?

A queue can be implemented by using 2 stacks:-

1. An element is inserted in the queue by pushing it into stack 1
2. An element is extracted from the queue by popping it from the stack 2
3. If the stack 2 is empty then all elements currently in stack 1 are transferred to stack 2 but in the reverse order
4. If the stack 2 is not empty just pop the value from stack 2.

### 4 :: Explain stacks and queues in detail?

A stack is a data structure based on the principle Last In First Out. Stack is container to hold nodes and has two operations - push and pop. Push operation is to add nodes into the stack and pop operation is to delete nodes from the stack and returns the top most node.

A queue is a data structure based on the principle First in First Out. The nodes are kept in an order. A node is inserted from the rear of the queue and a node is deleted from the front. The first element inserted in the first element first to delete.

### 5 :: Tell me what are priority queues?

A priority queue is essentially a list of items in which each item has associated with it a priority
Items are inserted into a priority queue in any, arbitrary order. However, items are withdrawn from a priority queue in order of their priorities starting with the highest priority item first.

Priority queues are often used in the implementation of algorithms