DSA · Theory

Representation of stack

Theory

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Representation of stack is a DSA idea you prove with undo typing, not with a slogan.

Representation of stack on the board — push / pop LIFO. Then say what undo typing looks like after.

Skip Representation of stack and pop on empty shows up in a tiny editor.

Use Representation of stack when undo typing must stay clear. If a simpler DSA step works, use that instead.

If undo typing breaks under Representation of stack, check pop on empty first.

Place Representation of stack next to nearby DSA work — push / pop LIFO is the link.

One breath for Representation of stack, then undo typing, then pop on empty. Sit down.

Diagram

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

Exam tip

For Representation of stack: definition + a tiny editor + one failure.

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

Representation of stack — stack is LIFO: push/pop from the same end.