Ozon Tech Challenge 2020 (Div.1 + Div.2, Rated, T-shirts + prizes!)
5 problems from Ozon Tech Challenge 2020 (Div.1 + Div.2, Rated, T-shirts + prizes!) (contest 1305), difficulty 800-3500. 1/5 solutions verified against sample I/O.
Ozon Tech Challenge 2020 (Div.1 + Div.2, Rated, T-shirts + prizes!)
Special | 5 problems | 1/5 verified | Difficulty 800-3500 | 31m 9s
| # | Problem | Rating | Tags | Accepted | Time | ✓ |
|---|---|---|---|---|---|---|
| A | Kuroni and the Gifts | 800 | brute-force, constructive-algorithms, greedy | 14,644 | 1m 48s | |
| B | Kuroni and Simple Strings | 1200 | constructive-algorithms, greedy, strings | 12,397 | 16m 28s | |
| D | Kuroni and the Celebration | 1900 | constructive-algorithms, dfs-and-similar, interactive | 5,362 | 3m 8s | |
| E | Kuroni and the Score Distribution | 2200 | constructive-algorithms, greedy, implementation | 3,272 | 7m 11s | |
| H | Kuroni the Private Tutor | 3500 | binary-search, greedy | 173 | 2m 34s | ✓ |
CF 1305E - Kuroni and the Score Distribution
We are asked to construct a strictly increasing sequence of integers $a1 < a2 < dots < an$, all between 1 and $10^9$, such that a specific combinatorial condition on triples is satisfied.
CF 1305H - Kuroni the Private Tutor
We are given an exam with a fixed number of questions, where each question contributes either 0 or 1 point to each student.
CF 1305D - Kuroni and the Celebration
We are given a fixed tree with up to 1000 vertices. Somewhere in this tree there is a hidden root vertex $r$, which represents Kuroni’s hotel. The structure of the tree is known, but the root is not.
CF 1305B - Kuroni and Simple Strings
The algorithm itself is correct. The bug is in the editorial's test harness code, not in the algorithm. In the posted solution, the pairs initialization was accidentally split across lines: That formatting artifact can cause issues when copied, and more importantly, the helper…
CF 1305A - Kuroni and the Gifts
Yes, the inequality $nu(n) le 2^{l(n) - lambda(n)}$ holds for all positive integers $n$. Consider an addition chain of minimal length $l(n)$ and let $lambda(n)$ be the length of a shortest chain consisting only of doubling steps.