Recall & Review
beginner
What is a stack in data structures?
A stack is a collection where elements are added and removed in a last-in, first-out (LIFO) order. Think of it like a stack of plates where you add or remove the top plate only.
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beginner
What are the two main operations of a stack?
The two main operations are push (to add an element on top) and pop (to remove the top element).
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intermediate
How is a stack implemented using an array?
A stack using an array keeps track of the top index. Push adds an element at the next top position, and pop removes the element at the current top, then moves the top down.
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intermediate
What happens if you try to push an element when the stack is full in an array implementation?
This is called a stack overflow. Since the array has a fixed size, you cannot add more elements beyond its capacity.
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beginner
What is the time complexity of push and pop operations in a stack implemented using an array?
Both push and pop operations take constant time, O(1), because they only add or remove the top element without shifting other elements.
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Which operation removes the top element from a stack?
✗ Incorrect
The pop operation removes the top element from the stack.
What does 'LIFO' stand for in the context of a stack?
✗ Incorrect
LIFO means Last In, First Out, describing how the last added element is the first to be removed.
What is the initial value of the 'top' index in an empty stack implemented with an array?
✗ Incorrect
The top index starts at -1 to indicate the stack is empty.
What happens when you try to pop from an empty stack?
✗ Incorrect
Popping from an empty stack causes a stack underflow error.
Which of these is NOT a stack operation?
✗ Incorrect
insertAtBottom is not a standard stack operation.
Explain how push and pop operations work in a stack implemented using an array.
Think about how the top index changes with each operation.
You got /4 concepts.
Describe what stack overflow and stack underflow mean in the context of array-based stacks.
Consider what happens when you exceed or go below stack limits.
You got /4 concepts.