Recall & Review
beginner
What is a stack in data structures?
A stack is a collection where elements are added and removed from only one end called the top. It follows the Last In, First Out (LIFO) principle.
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beginner
Explain the LIFO principle in simple terms.
LIFO means the last item you put in is the first one you take out, like a stack of plates where you take the top plate first.
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beginner
What are the two main operations of a stack?
The two main operations are push (to add an item on top) and pop (to remove the top item).
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intermediate
What happens if you try to pop from an empty stack?
This is called underflow. It means there is no item to remove because the stack is empty.
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intermediate
How does a stack differ from a queue?
A stack uses LIFO (last in, first out), while a queue uses FIFO (first in, first out). In a stack, you remove the last added item first; in a queue, you remove the oldest item first.
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Which operation adds an element to the top of a stack?
✗ Incorrect
Push adds an element to the top of the stack.
What does LIFO stand for in the context of stacks?
✗ Incorrect
LIFO means the last element added is the first one removed.
If you pop an element from a stack, which element do you remove?
✗ Incorrect
Pop removes the top element from the stack.
What is the term for trying to pop from an empty stack?
✗ Incorrect
Underflow happens when popping from an empty stack.
Which data structure follows FIFO instead of LIFO?
✗ Incorrect
Queue follows FIFO (first in, first out).
Describe how a stack works and explain the LIFO principle with a real-life example.
Think about how you add and remove items from a pile.
You got /3 concepts.
List and explain the main operations of a stack and what happens during underflow.
Focus on adding/removing items and empty stack behavior.
You got /4 concepts.