Online worksheet ยท 1 of 4
Keep a rule true after every operation - Online practice 1
Read the information, then answer the questions. An adult may read the instructions aloud. Show your working where asked.
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Inventory starts at 3. Invariant: stock is a non-negative integer. Process these operations in order: remove 5; add 2; remove 4. A removal larger than stock is rejected WITHOUT changing stock. Positive valid additions/removals otherwise update it. Every operation is independent and checked against current state.
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- Trace stock after each operation from 3: remove 5, add 2, remove 4.
- Why would checking stock only when the screen first opens be insufficient?
- What should be recorded or shown when the first removal is rejected?
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