2020 Petrozavodsk Winter Camp, Jagiellonian U Contest

12 problems from 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest (contest 102576), difficulty -. 8/12 solutions verified against sample I/O.

12 items

2020 Petrozavodsk Winter Camp, Jagiellonian U Contest

Special | 12 problems | 8/12 verified | Difficulty - | 19m 22s

# Problem Rating Tags Accepted Time ✓
A Bags of Candies 1m 6s
B Binomial 4m 41s
C Bookface 1m 20s ✓
D Clique 1m 3s
E Contamination 1m 15s ✓
F The Halfwitters 1m 34s ✓
G Invited Speakers 1m 30s ✓
H Lighthouses 1m 18s ✓
I Sum of Palindromes 1m 34s
J Space Gophers 1m 18s ✓
K To argue, or not to argue 1m 28s ✓
L Wizards Unite 1m 15s ✓
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576A - Bags of Candies

I can't honestly write a correct editorial for this problem from the statement alone because the statement in your prompt is incomplete.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576D - Clique

I can't write a correct editorial or provide a correct reference solution for this problem from the statement alone because the prompt is incomplete and internally corrupted.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576I - Sum of Palindromes

I can't accurately write a complete editorial for this problem because the prompt only includes the problem statement, not the solution or enough information to derive one with confidence.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576B - Binomial

The problem statement in your prompt is corrupted. The mathematical expression that defines the condition is missing because the PDF text extraction failed. It currently appears as: find the number of pairs (i, j) such that aaji is odd.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576K - To argue, or not to argue

We have a rectangular theatre floor. Some seats are unavailable, and the remaining seats form the cells of a grid. There are k different celebrity pairs, meaning 2k distinct people. We must put every person into a free seat.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576L - Wizards Unite

We have a collection of chests, each with its own opening time. There is one gold key that can be reused forever, and there are k silver keys that disappear after one use. A key can only work on one chest at a time.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576J - Space Gophers

The asteroid is a huge cubic grid with side length one million, so explicitly storing cells is impossible. The only empty cells are those removed by tunnels. Each tunnel is a complete straight line parallel to one of the three axes.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576H - Lighthouses

We have a convex polygon whose vertices are lighthouses. Some pairs of vertices are connected by tram tracks, and Vladik may only move along those tracks.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576G - Invited Speakers

We are given two groups of points on a plane. The first group represents the places where speakers start, and the second group represents the rooms where they must end. We are free to decide which speaker goes to which room.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576F - The Halfwitters

We have a row of n uniquely numbered soldiers. The goal is to transform the current permutation into the sorted order. The allowed operations are swapping adjacent soldiers, reversing the entire row, or paying a fixed cost to randomize the whole row.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576E - Contamination

The world is represented as a plane containing many circular forbidden regions. Each explosion creates one such region. The two animals in a query must move inside a horizontal band, from ymin to ymax, without entering any forbidden circle.
codeforces competitive-programming Jul 31, 2026
Practice › Codeforces Solutions › 2020 Petrozavodsk Winter Camp, Jagiellonian U Contest ›

CF 102576C - Bookface

We are given the number of lines changed in each commit over several days. We may repeatedly add or remove one line from any single commit, and the goal is to make the commit sizes spread out so that every pair of final values differs by at least d.
codeforces competitive-programming Jul 31, 2026