Assessment Solutions and Scoring
Use only after the first independent attempt. Each numbered answer calibrates the matching competency; apply the 0–3 rubric.
A01 / C01
State graph/domain, path validity, objective/units, tie policy, constraints, error and resource policies. Disconnected vertices after complete finite exploration imply no path; a stopped incomplete search implies unknown. Accept relational outputs if intentional.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A02 / C02
Greedy chooses 5+1+1+1 (four coins); 4+4 uses two, and no single 8 coin exists. DP over remaining amount or breadth-first sum search is sound with positive denominations and explicit base/unreachable states.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A03 / C03
Use the partition invariant and strictly decreasing natural hi-lo. Midpoints 2 then 1 then 0 produce final boundary 1. Empty input returns 0 without indexing. Missing the out-of-range guard for membership is a substantive gap.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A04 / C04
{a,b,c}. Reverse adjacency of c contains b, of b contains a and c. A visited set prevents infinite cycling. c belongs even without taking an edge. d does not reach c.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A05 / C05
2**n+n(n-1)(n-2) matches all three values and differs at 3. A stated recurrence with base cases and a proof, or another argument over the full domain, is needed; more samples alone cannot settle an unrestricted rule.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A06 / C06
All reachable values are even: 2 is even, +4 and multiplication by 3 preserve evenness. Thus 7 is impossible. Evenness is only necessary; it alone supplies no path to a particular even target.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A07 / C07
B(0)=0; for positive a, use one plus the minimum reachable B(a-3), B(a-5). Positive coins ensure smaller dependencies. [3,5] has two coins; no denomination is 8, so one is impossible. Target 0 returns []; target 1 returns None.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A08 / C08
It is 1-minimal under single deletion: deleting from length 3 yields length 2, which passes. A length-1 subsequence still fails. The algorithm has not established global minimality; report both the predicate and permitted reductions.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A09 / C09
Use (remaining amount, remaining denomination set), or process denominations in a fixed order with state (index, remaining amount). For the latter, include/exclude each coin and advance the index, so the index distance to the end decreases. Reject an answer that uses a coin again under the new contract.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.
A10 / C10
State the exact observed mismatch, fixture and command; name the deploy as a hypothesis; record unfinished checks, next update and responsible role. Reproduce on pre/post-change versions or isolate a transformation with the same fixture. Do not claim causation, a fix, or a safe rollback without supporting checks.
Repair: redo the linked practice task, then explain a changed input or assumption without this key.