2022-2023 ICPC, NERC, Southern and Volga Russian Regional Contest (Online Mirror, ICPC Rules, Preferably Teams)
Solutions for 2022-2023 ICPC, NERC, Southern and Volga Russian Regional Contest (Online Mirror, ICPC Rules, Preferably Teams) (contest 1765). 5/14 problems verified against sample I/O. Difficulty range: 800-2900.
2022-2023 ICPC, NERC, Southern and Volga Russian Regional Contest (Online Mirror, ICPC Rules, Preferably Teams)
Type: ICPC/IOI | Problems: 14 | Verified: 5/14 | Rating range: 800-2900 | Time: 45m 29s
| Problem | Name | Rating | Tags | Solve Time | Verified |
|---|---|---|---|---|---|
| A | Access Levels | 2400 | bitmasks, dsu, flows | 2m 29s | ✗ |
| B | Broken Keyboard | 800 | greedy | 8m 4s | ✓ |
| C | Card Guessing | 2600 | combinatorics, dp, probabilities | 4m 5s | ✓ |
| D | Watch the Videos | 1700 | binary-search, constructive-algorithms, two-pointers | 2m 16s | ✗ |
| E | Exchange | 1000 | brute-force, math | 4m 24s | ✗ |
| F | Chemistry Lab | 2200 | dp, geometry, probabilities | 2m 17s | ✗ |
| G | Guess the String | 2600 | constructive-algorithms, interactive, probabilities | 2m 3s | ✗ |
| H | Hospital Queue | 2200 | binary-search, graphs, greedy | 7m 24s | ✗ |
| I | Infinite Chess | 2800 | implementation, shortest-paths | 2m 25s | ✗ |
| J | Hero to Zero | 2900 | graph-matchings, math | 1m 43s | ✓ |
| K | Torus Path | 1500 | greedy, math | 2m 20s | ✓ |
| L | Project Manager | 2400 | brute-force, data-structures, implementation | 2m 16s | ✗ |
| M | Minimum LCM | 1000 | math, number-theory | 1m 26s | ✓ |
| N | Number Reduction | 1500 | greedy | 2m 17s | ✗ |
CF 1765N - Number Reduction
Codeforces 1765N: Number Reduction
CF 1765H - Hospital Queue
Got it. Let’s carefully trace what is happening. The previous solution attempt fails because it misinterprets the keyboard behavior. Mishka’s keyboard alternates between single-letter and double-letter presses globally, not per character. That is the key subtlety.
CF 1765M - Minimum LCM
We are asked to split a given integer n into two positive parts a and b so that their sum stays fixed at n. Among all such splits, we want the pair that makes the least common multiple of a and b as small as possible.
CF 1765L - Project Manager
Codeforces 1765L: Project Manager
CF 1765K - Torus Path
We are given a square grid of size $n times n$ where each cell has a non-negative integer. A chip starts at the top-left corner, and we want to move it to the bottom-right corner.
CF 1765I - Infinite Chess
Codeforces 1765I: Infinite Chess
CF 1765J - Hero to Zero
We are given two arrays, a and b, both of length n. From these, we can build a matrix c where each entry c[i][j] is the absolute difference The allowed operations are of two types: we can increment or decrement entire rows or columns, which affects multiple elements…
CF 1765G - Guess the String
We are asked to reconstruct a hidden binary string of length $n$, knowing that its first character is always '0'. We cannot read the string directly.
CF 1765E - Exchange
For input n = 1, k = 1: - Deck: 4 cards, one of each suit. - Sliding window k = 1 means Monocarp looks at the last card drawn (or zero for the first card) and guesses the least frequent suit.
CF 1765B - Broken Keyboard
We are asked to determine whether a given word could have been typed on a keyboard with a very specific malfunction: every other keystroke produces the letter twice instead of once.
CF 1765F - Chemistry Lab
We have a chemistry lab scenario where Monocarp can buy contracts that give him unlimited access to specific solutions of an acid. Each contract specifies the concentration of the solution, the cost to sign the contract, and the price he can sell it for.
CF 1765D - Watch the Videos
We are given a sequence of videos, each with a download size, and a fixed disk capacity that limits how many megabytes can be stored at once. Each video takes time proportional to its size to download, and once downloaded it can be watched in exactly one minute.
CF 1765C - Card Guessing
We are dealing with a long sequence of independent random experiments: a deck contains exactly four suits, and each suit appears exactly (n) times, so the total length is (4n). The deck is shuffled uniformly at random, so every permutation is equally likely.
CF 1765A - Access Levels
Each document is described by which developers should be able to open it. So every column of the input matrix is a subset of developers: those rows where the value is one form the “approved set” for that document.