XXV Interregional Programming Olympiad, Vologda SU, 2023

10 problems from XXV Interregional Programming Olympiad, Vologda SU, 2023 (contest 104314), difficulty -. 4/10 solutions verified against sample I/O.

10 items

XXV Interregional Programming Olympiad, Vologda SU, 2023

Special | 10 problems | 4/10 verified | Difficulty - | 16m 25s

#	Problem	Time	✓
A	Natasha and Cats	1m 6s	✓
B	Inequalities	1m 12s	✓
C	Regular expression	1m 6s	✓
D	Antique Clock	1m 52s
E	Bridge Construction	1m 16s	✓
F	Fragment	3m 13s
G	Unusual Calculator	1m 32s
H	Game Case	1m 56s
I	Cutting a Chain	1m 48s
J	Refactoring	1m 24s

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314J - Refactoring

We are given two non-negative integers, a and n. A program starts with a value b = 0 and then applies the same update step exactly n times: b := (b - a) & a Here subtraction and bitwise AND are done on 64-bit integers using two’s complement arithmetic.

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314I - Cutting a Chain

We are given a chain of $N$ numbered rings arranged in a line. The traveler wants to be able to pay exactly one ring per day for $N$ consecutive days, but he is allowed to cut the chain beforehand into separate usable pieces.

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314H - Game Case

We are given a small set of cards, each card showing a pair of integers. One of these cards is secretly the “prize” card. The first player sees only the left number of that card, the second player sees only the right number.

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314F - Fragment

We are repeatedly building a growing sum of very specific numbers. The k-th summand is a number made of a single digit 2 at both ends, with zeros filling the middle as the number grows, starting from 2, then 22, then 202, then 2002, and so on.

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314G - Unusual Calculator

We are given a state consisting of two integers, and we are allowed to transform this pair using exactly three reversible operations. One operation subtracts the second value from the first, another adds the second value to the first, and the third swaps the two coordinates.

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CF 104314D - Antique Clock

We are looking at a continuous analog clock where the hour and minute hands move smoothly rather than jumping once per minute. The minute hand completes a full circle in 60 minutes, while the hour hand completes a full circle in 12 hours.

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CF 104314E - Bridge Construction

We are given a grid that represents an archipelago. Each cell is either land, marked as 1, or water, marked as 0. Any two land cells that touch up, down, left, or right belong to the same island, so the grid naturally splits into multiple connected components of 1s.

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CF 104314B - Inequalities

We are given a row that alternates between empty positions and fixed comparison symbols. There are $N+1$ positions that must be filled with distinct numbers from 1 to $N+1$, and between every two neighboring positions there is exactly one constraint, either “<” or “”…

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314A - Natasha and Cats

We are told that Natasha has cats, and each cat behaves in a very rigid way during the night. Every time a cat “acts”, it produces exactly the same effect: a fixed number of items fall, from level A down to level B, and Natasha hears a total of N falling events in total.

Practice › Codeforces Solutions › XXV Interregional Programming Olympiad, Vologda SU, 2023 ›

CF 104314C - Regular expression

We are asked to construct a single regular expression over decimal digits that accepts exactly those integers whose digits can be rearranged to form a number divisible by 6. A number is divisible by 6 if and only if it is divisible by 2 and by 3.