The twelve problems
Each card below summarises one division and links to my full write-up for that division. Problem titles are confirmed against the official results page; paraphrases are my own.
Bronze division
1. Majority Opinion — find every hay type that can become unanimous via >½ focus-group passes.
2. Cannonball — simulate Bessie bouncing on a number line with jump pads and breakable targets.
3. Balancing Bacteria — minimum number of decreasing-prefix sprays to zero out an array.
Silver division
1. Cowmpetency — lexicographically smallest sequence given "first index exceeding running max" constraints.
2. Potion Farming — greedy on a tree to maximise potions collected within minimum-traversal walks.
3. Cowlendar — divisor enumeration: find all L with ≥ 4 weeks/month and ≤ 3 distinct remainders.
Gold division
1. Walking in Manhattan — query cow positions after a long deterministic NE walk on a grid road network.
2. Cowmpetency — count valid score sequences under the same "first to exceed" constraints, mod 1e9+7.
3. Nap Sort — partition values between Bessie's sort pile and napping helpers to minimise wall-clock time.
Platinum division
1. Island Vacation — random-walk-with-termination probabilities on a graph whose edges lie in ≤ 1 simple cycle.
2. Merging Cells — exact probability each label survives a uniform-random adjacent-merge process.
3. Mooball Teams III — count red/blue assignments separable by an axis-aligned line, both teams non-empty.
How I'm reading this contest
- Bronze and Silver are the divisions I'm racing the clock on. The write-ups for those pages include the C++ I'd submit.
- Gold and Platinum are stretch reading. I write the algorithm sketch and a reference C++ solution, then re-implement from memory later in the week.
- Cowmpetency appears twice — Silver wants any valid sequence, Gold wants the count over a much larger N. Same combinatorial skeleton, very different scale.