USACO 2015 January · Platinum · did not exist yet
Why there is no Platinum here. In January 2015 USACO ran a three-division contest:
Bronze (4 problems), Silver (3), and Gold (3). The Platinum division was introduced eleven months later,
in December 2015. The official January 2015 results page
(usaco.org/index.php?page=jan15results)
lists only Gold, Silver, and Bronze; there are no Platinum problems to write up. We've kept this page as
a stub so the per-division URL set stays consistent across contests, and we link to the real
destinations below.
What to do instead
- If you're a Gold-level student looking for Platinum-adjacent challenge in this round: Problem 3 of Gold (Grass Cownoisseur) is the hardest piece of January 2015 — SCC condensation plus DAG longest path. Master it before moving on.
- If you actually want the first Platinum problems ever written: jump to December 2015 Platinum — Max Flow (tree paths), High Card Low Card, and Counting Haybales. That round is the inaugural Platinum and the historical answer to "what was the first Platinum-level USACO problem set?".
- If you want a chronological tour: the next contest is December 2015 (introduction of Platinum), then January 2016 onward, all indexed from the Past Problems page.
Timeline check
| Contest | Divisions | Notes |
|---|---|---|
| USACO 2014 December | Bronze / Silver / Gold | Last 3-division December. |
| USACO 2015 January | Bronze / Silver / Gold | This page's contest. No Platinum. |
| USACO 2015 February | Bronze / Silver / Gold | Still 3 divisions. |
| USACO 2015 US Open | Bronze / Silver / Gold | Still 3 divisions. |
| USACO 2015 December | Bronze / Silver / Gold / Platinum | First-ever Platinum. |
| 2016 onward | 4 divisions every round | Standard format we know today. |
Source for divisions per contest: each contest's results page on usaco.org.