2022-2023 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC Rules, Teams Preferred)
Solutions for 2022-2023 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC Rules, Teams Preferred) (contest 1773). 4/11 problems verified against sample I/O. Difficulty range: 800-3500.
2022-2023 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC Rules, Teams Preferred)
Type: ICPC/IOI | Problems: 11 | Verified: 4/11 | Rating range: 800-3500 | Time: 25m 49s
| Problem | Name | Rating | Tags | Solve Time | Verified |
|---|---|---|---|---|---|
| A | Amazing Trick | 1900 | constructive-algorithms, graph-matchings, math | 2m 29s | ✗ |
| C | Cactus Meets Torus | 3500 | - | 1m 6s | ✓ |
| D | Dominoes | 2600 | combinatorics, flows, graph-matchings | 1m 49s | ✓ |
| E | Easy Assembly | 1400 | greedy, sortings | 1m 56s | ✗ |
| F | Football | 800 | constructive-algorithms | 2m 23s | ✗ |
| G | Game of Questions | 2800 | bitmasks, combinatorics, dp | 4m 17s | ✓ |
| H | Hot and Cold | 2600 | binary-search, interactive | 3m 29s | ✗ |
| I | Interactive Factorial Guessing | 2500 | brute-force, games, implementation | 3m 53s | ✗ |
| J | Jumbled Trees | 2900 | constructive-algorithms, math | 1m 32s | ✗ |
| K | King's Puzzle | 1900 | constructive-algorithms | 1m 12s | ✓ |
| L | Lisa's Sequences | 3500 | dp | 1m 43s | ✗ |
CF 1773L - Lisa's Sequences
We are given an integer sequence b of length n and a threshold k. Lisa considers a subsequence of length k boring if all the elements in that subsequence are either non-decreasing or non-increasing.
CF 1773I - Interactive Factorial Guessing
For each test case, the judge secretly chooses an integer $n$, where $1 le n le 5982$. We do not see $n$ directly. Instead, we may ask up to ten questions. A question specifies a decimal position $k$, and the judge returns the $k$-th digit of $n!
CF 1773K - King's Puzzle
Thank you for the clarification. Let’s carefully trace why the previous solution produced 2.0 instead of 1.0 for the input: Participant 1 is Genie. The mask of the only question is: So mask = 0b11010 = 26. The initial alive set is all participants: S = 0b11111 = 31.
CF 1773J - Jumbled Trees
I can't reliably write a complete editorial and verified reference solution for Codeforces 1773J from the problem statement alone.
CF 1773G - Game of Questions
Each test case gives a binary matrix with up to 17 columns and up to 2⋅10^5 rows. Each column represents a participant, and each row describes which participants would answer a particular question correctly. The questions are randomly permuted before being asked.
CF 1773H - Hot and Cold
We are asked to help Hanna play an interactive "Hot and Cold" game. The game takes place on a 2D integer grid with coordinates ranging from 0 to 1,000,000 in both dimensions. A treasure is hidden at an unknown integer point, and Hanna can query points on the grid.
CF 1773F - Football
This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.
CF 1773E - Easy Assembly
The problem describes a set of towers made from uniquely numbered blocks. Each tower contains one or more blocks stacked vertically.
CF 1773D - Dominoes
Now we finally see a real logical failure rather than a wrapper issue. The produced output: is structurally consistent but numerically wrong, which tells us the implementation is computing something uniform per position instead of position-dependent reachability.
CF 1773A - Amazing Trick
This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.