2024-2025 ICPC, Swiss Subregional

12 problems from 2024-2025 ICPC, Swiss Subregional (contest 105461), difficulty -. 12/12 solutions verified against sample I/O.

12 items

2024-2025 ICPC, Swiss Subregional

ICPC/IOI | 12 problems | 12/12 verified | Difficulty - | 12m 41s

#	Problem	Time	✓
A	Matrix Minors	1m 21s	✓
B	Digital Products	1m 2s	✓
C	Concert Lineup	57s	✓
D	LSB	1m 2s	✓
E	Lighting the Street	1m 9s	✓
F	Autobahn Optimization	59s	✓
G	Contrived Intelligence	57s	✓
H	Z\u00fcrich Trams	1m 19s	✓
I	Periodic Recurrence	57s	✓
J	Gibberish	1m 3s	✓
K	Cheater Detector	58s	✓
L	Drawing Rectangles	57s	✓

Practice › Codeforces Solutions › 2024-2025 ICPC, Swiss Subregional ›

CF 105461K - Cheater Detector

We are given a set of students where some pairs are known to have exchanged homework. Each report is an undirected edge between two students, meaning those two are connected in a “cheating interaction” graph.

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CF 105461H - Zürich Trams

The network of Zurich stations forms a tree, so between any two stations there is exactly one simple path. On top of this static structure, there are several trams.

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CF 105461J - Gibberish

We are dealing with a hidden permutation of positions from 1 to n. Whenever we send a word of length n, the system rearranges the letters according to this fixed permutation and returns the result.

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CF 105461G - Contrived Intelligence

We are dealing with a hidden integer-coefficient polynomial $P(x)$, but we never evaluate it directly. Instead, we interactively query an index $k$, and the judge tells us how many values among $P(1), P(2), dots, P(k)$ are divisible by $k$.

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CF 105461E - Lighting the Street

We are given a straight street represented as a continuous segment from 0 to L. There are n fixed lamp posts placed at integer coordinates along this segment. We are not allowed to choose their positions, only the type of bulb installed in each lamp post.

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CF 105461B - Digital Products

We are given a number $n$, and we consider every integer $x$ from 1 up to $n$. For each number $x$, we compute a value formed by multiplying all its decimal digits. If a number contains a zero digit, its digit product becomes zero.

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CF 105461D - LSB

We are given a system that allows us to construct new bitsets from an initial bitset $B0$. Each bitset has length $n$, and we can generate new ones using only a small set of operations: shifting left or right, XOR, and OR between previously constructed bitsets.

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CF 105461L - Drawing Rectangles

We are repeatedly choosing axis-aligned rectangles inside an $n times m$ grid whose corners lie on integer coordinates.

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CF 105461I - Periodic Recurrence

We are given a sequence generated by a linear recurrence modulo a fixed integer $M$. The sequence starts from two initial values $a0$ and $a1$, and every next element is formed by combining the previous two using fixed coefficients $A$ and $B$, then reducing the result modulo…

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CF 105461F - Autobahn Optimization

We are given a sequence of cars that arrive in a fixed order. Each car has a maximum possible speed, and we are allowed to assign each car to one of two lanes. The order of cars inside each lane is the same as the original order, so each lane forms a subsequence.

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CF 105461A - Matrix Minors

We are given a square matrix and asked to compute a very specific derived matrix. For every cell $(i, j)$, we conceptually remove row $i$ and column $j$ from the original matrix and compute the determinant of the remaining $(n-1) times (n-1)$ matrix.

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CF 105461C - Concert Lineup

We are maintaining a dynamic ordering of $n$ distinct items representing artists in a concert lineup. The lineup is stored as a sequence, and we repeatedly apply operations that depend on positions inside the current sequence. Each operation gives an even number $k$.