Central-European Olympiad in Informatics, CEOI 2020, Day 2 (IOI, Unofficial Mirror Contest, Unrated)
Solutions for Central-European Olympiad in Informatics, CEOI 2020, Day 2 (IOI, Unofficial Mirror Contest, Unrated) (contest 1403). 1/3 problems verified against sample I/O. Difficulty range: 2300-3200.
Central-European Olympiad in Informatics, CEOI 2020, Day 2 (IOI, Unofficial Mirror Contest, Unrated)
Type: ICPC/IOI | Problems: 3 | Verified: 1/3 | Rating range: 2300-3200 | Time: 20m 41s
| Problem | Name | Rating | Tags | Solve Time | Verified |
|---|---|---|---|---|---|
| A | The Potion of Great Power | 2400 | *special, 2-sat, binary-search | 2m 3s | ✗ |
| B | Spring cleaning | 2300 | *special, data-structures, dfs-and-similar | 14m 30s | ✗ |
| C | Chess Rush | 3200 | *special, combinatorics, dp | 4m 8s | ✓ |
CF 1403B - Spring cleaning
We are given a tree with N nodes, connected by N-1 edges. Each node may be a leaf, defined as a node with exactly one edge. Cleaning the tree involves selecting two different leaves and marking all edges along the shortest path between them as cleaned.
CF 1403C - Chess Rush
Let’s trace what the wrong behavior implies. Input: Grid: There are only 4 cells total. But the output is 9, which is suspiciously close to “counting something per cell plus neighbors” or “counting all 2x2 substructures / adjacency contributions”.
CF 1403A - The Potion of Great Power
We have a dynamic friendship network among N shamans, each living at a specific altitude H[i]. Initially, no shaman trusts anyone, and every day a single friendship either forms or dissolves. Each shaman can trust at most D others at any time.