2025-2026 ICPC, NERC, Northern Eurasia Finals (Unrated, Online Mirror, ICPC Rules, Teams Preferred)
13 problems from 2025-2026 ICPC, NERC, Northern Eurasia Finals (Unrated, Online Mirror, ICPC Rules, Teams Preferred) (contest 2181), difficulty 1200-3500. 4/13 solutions verified against sample I/O.
2025-2026 ICPC, NERC, Northern Eurasia Finals (Unrated, Online Mirror, ICPC Rules, Teams Preferred)
ICPC/IOI | 13 problems | 4/13 verified | Difficulty 1200-3500 | 25m 54s
| # | Problem | Rating | Tags | Accepted | Time | ✓ |
|---|---|---|---|---|---|---|
| A | Alphabet City | 1300 | binary-search, math, strings | 3,717 | 2m 6s | ✓ |
| B | Battle of Arrays | 1400 | data-structures, games, greedy | 5,659 | 1m 55s | |
| C | Cacti Classification | 3200 | binary-search, constructive-algorithms, interactive | 148 | 1m 51s | |
| D | Doorway | 2000 | binary-search, data-structures, sortings | 1,357 | 1m 22s | ✓ |
| E | Elevator Against Humanity | 2900 | brute-force, constructive-algorithms, greedy | 144 | 2m 30s | |
| F | Fragmented Nim | 1600 | games | 3,515 | 1m 51s | ✓ |
| G | Greta's Game | 2400 | binary-search, dp, graphs | 649 | 2m 9s | |
| H | Honey Cake | 1200 | brute-force, math, number-theory | 6,588 | 1m 45s | |
| I | Irrigation Interlock | 3500 | geometry | 50 | 2m 12s | |
| J | Jinx or Jackpot | 2300 | brute-force, dp, math | 708 | 1m 41s | |
| K | Knit the Grid | 3500 | 2-sat, constructive-algorithms, graphs | 66 | 2m 47s | |
| L | LLM Training | 2800 | math, string-suffix-structures | 133 | 2m 24s | |
| M | Medical Parity | 1700 | dp, strings | 3,475 | 1m 21s | ✓ |
CF 2181M - Medical Parity
We are given two binary strings, which we can think of as observed measurements from a medical test. The first string represents the recorded presence or absence of reactions to several allergens.
CF 2181L - LLM Training
We are given several token sequences, each sequence representing a text where some positions are produced by a language model and others are written directly by a user. Only the positions marked as generated contribute to the training loss.
CF 2181K - Knit the Grid
The canvas is a rectangular grid of cells, but the real structure lives on its grid graph: vertices are grid intersection points and edges connect adjacent intersections horizontally or vertically. Initially, some collection of simple cycles is drawn along these edges.
CF 2181I - Irrigation Interlock
We have two sets of points on a Cartesian plane: pumps scattered across a valley and reservoirs positioned on surrounding hills.
CF 2181J - Jinx or Jackpot
We are given a casino machine whose behaviour is determined by one hidden probability value. There is an array of probabilities, and the casino owner secretly picks one index uniformly at random at the start and fixes it forever.
CF 2181H - Honey Cake
We are given a rectangular cake with dimensions $w times h times d$. The goal is to divide this solid into exactly $n$ smaller rectangular pieces, all identical in size. The only allowed operations are cuts that are parallel to the faces of the cake.
CF 2181G - Greta's Game
Each round produces a choice of an integer at every position on a cycle. After the numbers are chosen, we look at each adjacent pair on the cycle and award one point to both endpoints whenever the left endpoint is strictly larger than the right endpoint.
CF 2181E - Elevator Against Humanity
We have a skyscraper with floors numbered from 1 up to very large numbers, and several people waiting for an elevator on different floors. Each person has a distinct starting floor and a distinct destination floor, and no two floors overlap.
CF 2181F - Fragmented Nim
We are asked to analyze a variation of the classical game of Nim. In the original Nim, players take turns picking a pile and removing any number of stones. The player who takes the last stone wins.
CF 2181D - Doorway
Each layer of the doorway is a one-dimensional segment between two fixed walls. Inside that segment, there are several rigid door blocks placed in a line, but each block is allowed to slide left or right as long as it does not overlap other blocks or cross the walls.
CF 2181A - Alphabet City
We are asked to calculate how many full sets of street signs can be made when one street's order is missing. Each street in Alphabet City has a name made from capital letters, and each street has an order for m identical signs.
CF 2181B - Battle of Arrays
We are asked to simulate a turn-based game between Alice and Bob. Each player starts with an array of positive integers. On their turn, a player picks any element from their own array and applies it against the maximal element in the opponent's array.
CF 2181C - Cacti Classification
We are dealing with a hidden connected graph that has a very restricted structure: it is a cactus, meaning every edge participates in at most one simple cycle.