Trace and implement a stack
See this course’s project requirements
A runnable fictional help-desk simulator with an undo stack, FIFO queue and small dependency graph, plus empty and cyclic case tests.
Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.
What to include
- An operation-to-structure map with three distinct retrieval rules.
- An undo trace with last-in-first-out and empty-state handling.
- A FIFO record with clear empty behavior.
- A four-node dependency plan ending with archive.
- A cycle diagnosis and justified repair record.
- A runnable stack/queue/dependency demonstration with boundary evidence.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
Actions are [draft, review]. The supplied list.pop() removes the last item.
A stack adds and removes at one end. Popping an empty Python list raises IndexError; the application should decide whether to reject or display no action before popping.
Trace and implement a stack — original worked practice
A stack adds and removes at one end. Popping an empty Python list raises IndexError; the application should decide whether to reject or display no action before popping.
Actions are [draft, review]. The supplied list.pop() removes the last item.
1. Step 1
Trace the current top.
You should see: review is the top action.
This keeps the rule and its observable result together.
2. Step 2
Pop once and record the remaining list.
You should see: draft remains.
This keeps the rule and its observable result together.
3. Step 3
Pop again, then guard the empty case with if stack.
You should see: The stack becomes empty; a further guarded undo changes nothing.
This keeps the rule and its observable result together.
4. Step 4
Add an edit and run two safe undo attempts.
You should see: An undo trace with last-in-first-out and empty-state handling.
This keeps the rule and its observable result together.
What to finish
An undo trace with last-in-first-out and empty-state handling.
Watch for this
Popping the first item from the list when the stated undo contract requires the most recently appended item.
How can I tell I understand it?
Explain and demonstrate the required distinction: A stack adds and removes at one end. Popping an empty Python list raises IndexError; the application should decide whether to reject or display no action before popping. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
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Sources and further reading
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Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
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