SDU Open 2023

12 problems from SDU Open 2023 (contest 104324), difficulty -. 12/12 solutions verified against sample I/O.

12 items

SDU Open 2023

Special | 12 problems | 12/12 verified | Difficulty - | 12m 2s

#	Problem	Rating	Tags	Accepted	Time	✓
A	SDU Open				55s	✓
B	From decreasing to increasing				52s	✓
C	Serial Representative				53s	✓
D	UFC				1m 12s	✓
E	Cultural Dissonance				45s	✓
F	Lost in the Jungle				1m 13s	✓
G	GCD Encryption				48s	✓
H	SDUcell				1m 11s	✓
I	Broken sword				1m 20s	✓
J	Chef Coder				49s	✓
K	Postal code				1m 15s	✓
L	Dream Team				49s	✓

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CF 104324K - Postal code

We are given a set of $n$ distinct postal codes, each written as a 5-digit string (leading zeros are allowed, so every code can be treated as a fixed-length string of length five over digits $0$ to $9$). Think of each postal code as a node in a graph.

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CF 104324L - Dream Team

We are trying to assemble a “team” from two pools of students. From the undergraduate pool we must choose exactly three distinct students, and the quality of this team is the sum of their strength values. From the graduate pool we choose exactly one student to act as a coach.

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CF 104324I - Broken sword

We are given a line of monsters, each with a strength value. Daniyar fights them using a sword that can remove a contiguous block of monsters in a single swing, but only up to a fixed length k in the current remaining lineup.

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CF 104324H - SDUcell

A user is walking through a city along a route made of straight street segments aligned with axes. Each segment is either purely horizontal or purely vertical, so at any moment the user’s position moves linearly in one coordinate while the other stays fixed.

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CF 104324J - Chef Coder

We are given a line of participants, each with two thresholds: a lower requirement $ai$, and a higher requirement $bi$, where $ai < bi$. Each participant becomes “satisfied” once they receive at least $ai$ steaks, and becomes “full” once they receive at least $bi$ steaks.

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CF 104324G - GCD Encryption

We are given a multiset of integers, originally arranged in some unknown order. The only structural clue about the original ordering is not about adjacency or sorting, but about a global arithmetic property tied to indices: if we take each element and add its position in the…

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CF 104324F - Lost in the Jungle

We are given a tree with n vertices, so there is exactly one simple path between any two nodes. Each vertex has a degree, and a traveler standing at a vertex chooses uniformly among its adjacent vertices and moves there in one step. This defines a simple random walk on the tree.

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CF 104324D - UFC

Two players independently choose an ordering of the same set of fighters numbered from 1 to n, where a larger number always represents a stronger fighter. They then play n rounds.

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CF 104324E - Cultural Dissonance

We are given a collection of $n$ toppings, each contributing a signed value to taste. A “dish” is defined by choosing any subset of these toppings, and its taste is simply the sum of values of the chosen elements.

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CF 104324A - SDU Open

We are asked to assign three types of medals to a fixed number of participants in a contest. Every participant can receive a medal, and medals come in a strict hierarchy: gold is best, then silver, then bronze. The rules do not directly give exact counts.

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CF 104324B - From decreasing to increasing

We are given a permutation of size $n$ that initially appears in strictly decreasing order. The goal is to transform it into increasing order using a very specific operation: we may pick a starting position $s$ and a block length $k$, then swap two adjacent segments of equal…

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CF 104324C - Serial Representative

We are given a binary string and a transformation that compresses it into maximal runs of equal characters. Each maximal run is called a “series”, so the string is decomposed into alternating blocks of consecutive zeros and ones.