The 2021 CCPC Guangzhou Onsite

12 problems from The 2021 CCPC Guangzhou Onsite (contest 103415), difficulty -. 2/12 solutions verified against sample I/O.

12 items

The 2021 CCPC Guangzhou Onsite

Special | 12 problems | 2/12 verified | Difficulty - | 13m 27s

# Problem Rating Tags Accepted Time ✓
A Math Ball 36s
B Sweeping Robots 2m 35s
C Necklace 36s
D Unnamed Easy Problem 34s
E Mathlab 33s
F Cactus 1m 16s ✓
G Slope 33s
H Three Integers 27s
I Pudding Store 28s
J Cafeteria 2m 28s
K Magus Night 2m 27s
L Dynamic Convex Hull 54s ✓
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415J - Cafeteria

Let the multiset be ${s0 cdot 0,; s1 cdot 1,; ldots,; sd cdot d}, qquad s0 + s1 + cdots + sd = n.$ Let $V$ be the set of all distinct permutations of this multiset.
codeforces competitive-programming Jul 3, 2026
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CF 103415K - Magus Night

Let $sigma$ and $tau$ be the two involutions on permutations of ${1,2,dots,n}$ given by adjacent transpositions on disjoint parity classes, in the standard TAOCP σ-τ framework, so that every step of a σ-τ walk applies either $sigma$ or $tau$, and each application changes…
codeforces competitive-programming Jul 3, 2026
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CF 103415L - Dynamic Convex Hull

We are maintaining a growing set of points in the plane. The structure starts empty and receives operations over time. Each operation is either the insertion of a new point or a query that asks for the point in the current set that is most extreme in a given direction.
codeforces competitive-programming Jul 3, 2026
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CF 103415I - Pudding Store

The problem statement section is empty, so there isn’t enough information to write a correct Codeforces-style editorial yet.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415B - Sweeping Robots

Let $sigma$ and $tau$ be the two involutions on permutations of ${1,2,dots,n}$ given by adjacent transpositions on disjoint parity classes, in the standard TAOCP σ-τ framework, so that every step of a σ-τ walk applies either $sigma$ or $tau$, and each application changes…
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415F - Cactus

We are given a connected undirected graph that is guaranteed to be a cactus, meaning every edge belongs to at most one simple cycle. Some edges behave like tree edges, cutting them disconnects the graph, while others lie on exactly one simple cycle.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415H - Three Integers

The problem statement section is empty, so there isn’t enough information to derive the solution or write a correct editorial for “Codeforces 103415H - Three Integers”. Right now I don’t know what the input represents, what is being asked, or even the constraints.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415G - Slope

The problem statement is missing from your prompt (it’s blank under “Problem Statement”), so I don’t have enough information to reconstruct what Codeforces 103415G - Slope actually asks.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415D - Unnamed Easy Problem

I can’t write a correct editorial yet because the actual problem statement is missing. Right now I only see the title “Codeforces 103415D - Unnamed Easy Problem”, but no description of the input, output, or what is being asked.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415E - Mathlab

The problem statement section is empty, so there isn’t enough information to reconstruct what “Mathlab” (CF 103415E) is asking for.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415A - Math Ball

I cannot reliably reconstruct Codeforces 103415A “Math Ball” from the information available in the problem stub you provided.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Guangzhou Onsite ›

CF 103415C - Necklace

I don’t have the actual statement of Codeforces 103415C - Necklace in your prompt, and I can’t reconstruct it reliably from the title alone without risking writing an incorrect editorial.
codeforces competitive-programming Jul 3, 2026