AGM 2021, Qualification Round

12 problems from AGM 2021, Qualification Round (contest 102968), difficulty -. 11/12 solutions verified against sample I/O.

12 items

AGM 2021, Qualification Round

Special | 12 problems | 11/12 verified | Difficulty - | 12m 48s

# Problem Rating Tags Accepted Time ✓
A Perfect Alliance 47s ✓
B Rainbow Array 1m 1s ✓
C Ohara's Bits 1m 7s ✓
D Data Integrity 52s ✓
E Two Gangs 48s ✓
F Japanese parser 1m 3s ✓
G Complete Journey 52s ✓
H KMP 50s ✓
I Orchards 2m 52s
J Pyra, Pyra, Pyraminx! 1m ✓
K Squares City 44s ✓
L Yet another roads problem 52s ✓
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CF 102968I - Orchards

Stopped thinking
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CF 102968C - Ohara's Bits

We are given two sequences. The first sequence contains patterns, each pattern being a number that we interpret in binary. The second sequence contains numbers that are concatenated, in order, into a single long binary string with no separators.
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CF 102968J - Pyra, Pyra, Pyraminx!

We are given a scrambled configuration of a Pyraminx, which is a tetrahedral twisty puzzle. Each test describes the full visible state of the puzzle as four triangular faces, each face being shown as a 1-3-5 triangular grid of colored stickers.
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CF 102968G - Complete Journey

We are given an undirected connected graph where every edge has a distinct weight, interpreted as “beauty”. Between any two vertices, you do not get to pick an arbitrary path in the usual sense.
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CF 102968L - Yet another roads problem

We are given a collection of cities, each city having an integer value representing its population. We are allowed to build roads between pairs of cities. If we connect two cities with populations a and b, the “benefit” of that road is gcd(a, b).
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CF 102968K - Squares City

We are given a very large square grid of size $N times N$, where $N$ is always a power of two. Only the cells above the secondary diagonal are relevant, meaning all cells $(X, Y)$ such that $X + Y le N$. This forms a triangular region.
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CF 102968F - Japanese parser

We are given a continuous string made of lowercase Latin letters and punctuation symbols. There are no spaces in the input, so everything is concatenated into one sequence that mixes “word-like” romanized syllables and standalone punctuation characters.
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CF 102968H - KMP

We are given a sequence of integers, and we want to count subsequences (so we pick indices in increasing order, not necessarily contiguous) with a special property on the values we picked.
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CF 102968E - Two Gangs

We are given two rooted trees over the same set of cities. Each city is a node that exists in both trees, but the parent-child relationships differ between the two structures. So we should think of the same set of nodes being organized twice, in two independent hierarchies.
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CF 102968D - Data Integrity

We are given an undirected graph where each edge carries a label. Each label is an integer in the range from 0 to $2^k - 1$, since the value limit is of the form $VAL = 2^k - 1$.
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CF 102968B - Rainbow Array

The array represents a line of positions, each carrying a non-negative integer interpreted as a color. You are allowed to recolor positions, and recoloring a position has a fixed cost, independent of what new value you assign.
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CF 102968A - Perfect Alliance

We are given a directed graph of tribes, where each tribe is a node and some directed roads already exist between them. The goal is to make the entire graph strongly connected, meaning every tribe must be able to reach every other tribe following directed roads.
codeforces competitive-programming Jul 4, 2026