DSA · Theory

Stack Organisation

Theory

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Stack Organisation is a DSA topic. In plain words you use it for undo typing in a tiny editor. Don’t start with a slogan — start with that picture.

Smallest example: push / pop LIFO. Type it, run it, and say what you see. If you can do that from memory, you know Stack Organisation.

From the example next to this theory — Stack Organisation — stack is LIFO: push/pop from the same end.

Trap — pop on empty. Fix that before you talk about advanced DSA.

Viva — what is Stack Organisation? Then show push / pop LIFO. Then name the trap.

Diagram

    | 3 |  ← top (pop)
    | 2 |
    | 1 |
    LIFO

Exam tip

What is Stack Organisation? Show this: push / pop LIFO. Trap: pop on empty.

stack = []
stack.append(10)   # push
stack.append(20)
print(stack.pop()) # 20
print(stack[-1])   # peek → 10

Stack Organisation — stack is LIFO: push/pop from the same end.