ICPC Central Russia Regional Contest, 2021

15 problems from ICPC Central Russia Regional Contest, 2021 (contest 104454), difficulty -. 6/15 solutions verified against sample I/O.

15 items

ICPC Central Russia Regional Contest, 2021

ICPC/IOI | 15 problems | 6/15 verified | Difficulty - | 22m 58s

# Problem Rating Tags Accepted Time ✓
A Puzzle generator 1m 15s
B Shooting 1m 34s ✓
C Pisano period 1m 57s
D Bucket of sand 1m 14s
E Brass Birmingham: coins 1m 37s
F Brass Birmingham: cities 1m 58s
G Brass Birmingham: beer 1m 16s
H Brass Birmingham: roads 1m 30s ✓
I Problem 3n+1 1m 1s ✓
J Interesting numbers 1m 59s
K To-do list 1m 24s
L Permutations and sums 1m 26s ✓
M Three cushion carom 1m 52s
N Just another array problem 1m 11s ✓
O Sea Battle 1m 44s ✓
Practice › Codeforces Solutions › ICPC Central Russia Regional Contest, 2021 ›

CF 104454O - Sea Battle

The grid is a fixed 10 by 10 battlefield where each cell is either water or part of a ship. Ships are already placed correctly before any queries start, and every ship is a connected shape formed by adjacent cells horizontally or vertically.
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CF 104454M - Three cushion carom

Your prompt is missing the actual problem statement for “Codeforces 104508A - Area in Convex” (it only contains A under Problem Statement and nothing else).
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CF 104454N - Just another array problem

We are given a sequence that starts out already sorted in non-decreasing order. After that, the sequence is not modified by insertions or deletions, but it can be cyclically rotated many times, either to the left or to the right.
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CF 104454L - Permutations and sums

We are given a set of integers from 1 to n, and we are allowed to place them in any order as a permutation. We care only about what happens at the very beginning of that permutation. There are two possible structures we are trying to achieve.
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CF 104454K - To-do list

We are given a collection of tasks, each task having its own repetition period measured in days. If a task has value $ai$, then once it is initially completed on day 0, it must be repeated again on days $ai, 2ai, 3ai,dots$, as long as those days fall within the next $k$ days…
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CF 104454J - Interesting numbers

Your prompt is missing the actual problem statement for “Codeforces 104508A - Area in Convex” (it only contains A under Problem Statement and nothing else).
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CF 104454I - Problem 3n+1

We are given an interval of consecutive integers starting from a large value s, specifically all integers in the range [s, s + w - 1].
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CF 104454H - Brass Birmingham: roads

Each of the four players builds two kinds of things on a shared map of cities. First, they place industry tokens into specific cities. A city can contain multiple industries if several tokens land there across all players.
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CF 104454F - Brass Birmingham: cities

Your prompt is missing the actual problem statement for “Codeforces 104508A - Area in Convex” (it only contains A under Problem Statement and nothing else).
codeforces competitive-programming Jun 30, 2026
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CF 104454G - Brass Birmingham: beer

We are given a collection of cities connected by already built roads, forming an undirected graph. In some of these cities there are breweries, each containing exactly one unit of beer, and in some cities there are factories that Igor wants to open.
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CF 104454E - Brass Birmingham: coins

Each player has a stack of coins, and each coin has a denomination from 1 to n. The stacks are ordered from bottom to top, and only the top coin of each stack is accessible at any moment.
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CF 104454D - Bucket of sand

We are given a vertical conical bucket characterized by its height and the diameter of its top opening. Into the exact center of the base, sand is poured continuously, forming a symmetric conical pile whose shape is determined by a fixed angle at its base.
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CF 104454C - Pisano period

Your prompt is missing the actual problem statement for “Codeforces 104508A - Area in Convex” (it only contains A under Problem Statement and nothing else).
codeforces competitive-programming Jun 30, 2026
Practice › Codeforces Solutions › ICPC Central Russia Regional Contest, 2021 ›

CF 104454B - Shooting

Each move in this problem is a shot that lands on one of $k$ concentric rings, and each ring contributes a fixed score equal to its index. So a shot is simply a value from 1 to $k$.
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Practice › Codeforces Solutions › ICPC Central Russia Regional Contest, 2021 ›

CF 104454A - Puzzle generator

We are given a partially specified $n times n$ grid, but in reality only the first row is fixed. That row is a permutation of the numbers from 1 to $n$, meaning every value appears exactly once.
codeforces competitive-programming Jun 30, 2026