Basic Operations in Stack Data Structure

Stack is a linear data structure that follows the LIFO (Last In First Out) principle for inserting and deleting elements from it.

In order to work with a stack, we have some fundamental operations that allow us to insert, remove, and access elements efficiently. These include:

• push() to insert an element into the stack
• top() Returns the top element of the stack.
• pop() to remove an element from the stack
• isEmpty() returns true if the stack is empty else false.
• size() returns the size of the stack.

We will now see how to perform these operations on Stack.

Push Operation in Stack:

Push operation is used to insert an element onto the top of the stack.

Time Complexity: O(1), since insertion at the top takes constant time.
Auxiliary Space: O(1)

Note: If the stack is implemented using a fixed-size array, inserting an element into a full stack will cause an overflow condition.

Top or Peek Operation in Stack:

Top or Peek operation is used to get the top element of the stack.

3 

Time Complexity: O(1)
Auxiliary Space: O(1)

Pop Operation in Stack:

Pop operation is used to remove an element from the top of the stack.

The items are popped in the reversed order in which they are pushed.

3 2 1 

Time Complexity: O(1)
Auxiliary Space: O(1)

Note: If a stack is empty, deleting an element will cause an underflow condition.

isEmpty Operation in Stack:

isEmpty operation is a boolean operation that is used to determine if the stack is empty or not. This will return true if the stack is empty, else false.

Stack is empty.
Stack is not empty.

Time Complexity: O(1)
Auxiliary Space: O(1)

Size Operation in Stack:

Size operation in Stack is used to return the count of elements that are present inside the stack. 

0
2

Time Complexity: O(1)
Auxiliary Space: O(1)