usaco.org/index.php?page=viewproblem2&cpid=…).
Round metadata
| Contest | USACO 2024 December |
|---|---|
| Window | Roughly Dec 13–16, 2024 (4-day window, single 4-hour personal timer) |
| Length per division | 4 hours (Dec/Jan/Feb format; US Open is the 5-hour round) |
| Problems per division | 3 |
| Total problems | 12 (Bronze 1–3, Silver 1–3, Gold 1–3, Platinum 1–3) |
| Scoring | IOI-style partial credit, 1000 points per problem, 3000 max per division |
| Allowed languages | C++17, Java, Python 3 (C++ is the default for almost all serious climbers) |
| Bronze cutoff (post-contest) | 700 / 3000 (for promotion to Silver next round) |
The contest at a glance
Bronze · 3 problems
1. Roundabout Rounding — chain vs. one-shot rounding, count divergent integers up to N.
2. Farmer John's Cheese Block — after each unit cube carve, count placements of a 1×1×N brick.
3. It's Mooin' Time — find candidate length-3 "moo" substrings, allowing one corrupted character.
Silver · 3 problems
1. Cake Game — circular cake, two players alternately eat from an end; sliding window of length K.
2. Deforestation — maximum trees removable while keeping K interval constraints satisfied (greedy + sweep).
3. 2D Conveyor Belt — N×N grid of conveyors, count unusable cells after each build (reverse BFS / DSU).
Gold · 3 problems
1. Cowdependence — for every x in 1..N, minimum groups of equal-label cows within x positions.
2. Interstellar Intervals — count R/B colorings of 1..N respecting an R/B/X string and disjoint equal-length intervals.
3. Job Completion — maximize jobs completed when each has a release time s and duration t (greedy + heap).
Platinum · 3 problems
1. All Pairs Similarity — sum Jaccard similarity of one cow's K-bit string against all N (subset sum / SOS DP).
2. It's Mooin' Time — minimum cost to plant ≥k non-overlapping "moos" for each k (DP / convex Lagrangian).
3. Maximize Minimum Difference — count permutations of 1..N maximizing min adjacent gap under K positional pins.
Per-division existing one-problem write-ups
These earlier pages each focus on a single highlighted problem from the round and stay in place; the new -full pages cover all three problems per division.
- Bronze · Roundabout Rounding — focused notes on problem 1.
- Silver · Cake Game — focused notes on problem 1.
- Gold · Cowdependence — focused notes on problem 1.
How to use this set
- Pick your division. Open the full division page and read the three statements before writing any code.
- Solve P1 first, P2 if time, P3 only if you're cruising. December problem 1s are usually the cheapest points.
- Time-box. 4 hours total. Don't spend more than ~90 minutes on a single problem without a working subtask submission.
- Compare to the reference C++. Each problem on the division page has a ~30–50 line reference solution. If yours is much longer, ask why.
- Verify with the editorial. Official editorials are linked from each problem page on usaco.org.