The 2021 CCPC Weihai Onsite

13 problems from The 2021 CCPC Weihai Onsite (contest 103428), difficulty -. 3/13 solutions verified against sample I/O.

13 items

The 2021 CCPC Weihai Onsite

Special | 13 problems | 3/13 verified | Difficulty - | 10m 24s

# Problem Rating Tags Accepted Time ✓
A Goodbye, Ziyin! 34s
B Subset 49s ✓
C Assign or Multiply 1m 2s
D Period 1m 15s ✓
E CHASE! 32s
F Stone 2m 13s
G Shinyruo and KFC 36s
H city safety 26s
I Distance 28s
J Circular Billiard Table 49s ✓
K Tiny Stars 44s
L shake hands 27s
M 810975 29s
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428M - 810975

The problem statement is missing, so there’s no way to reconstruct the actual task, constraints, or required algorithm.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428F - Stone

Let $q$ be a primitive $m$th root of unity and let $$N = n1 + cdots + nt.$$ Write each index in base $m$ form $$ni = m ai + ri,qquad 0 le ri < m,$$ and define $$A = a1 + cdots + at,qquad R = r1 + cdots + rt,$$ so that $N = mA + R$.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428L - shake hands

The problem statement for Codeforces 103428L - shake hands is missing in your prompt (it’s empty after “Problem Statement / Input / Output”).
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428K - Tiny Stars

I’m missing the actual problem content. Right now the prompt only contains the header for Codeforces 103428K - Tiny Stars, but the statement, input format, output format, and constraints are empty.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428J - Circular Billiard Table

We are dealing with a classical billiards dynamics setup, but restricted to a perfectly circular table. A ball starts on the boundary of the circle and is shot inward with a given direction, represented by an angle.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428I - Distance

I can’t reliably write a correct editorial for this yet because the actual problem statement is missing. Right now we only know the title “Distance”, but nothing about what “distance” is defined on, what the input represents, or what needs to be computed.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428H - city safety

I can write the full editorial, but I’m missing the actual problem content. The statement section you provided for “Codeforces 103428H - city safety” is empty, so there’s no definition of: what the graph/array/city structure is, what “safety” means, what operations…
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428G - Shinyruo and KFC

The problem statement is missing from your prompt, so there is no way to reconstruct the correct solution or write a meaningful editorial.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428B - Subset

We are given all integers from 0 up to N, and we need to choose exactly K distinct numbers from this range. For every chosen subset, we compute the XOR of all its elements, then look at the binary representation of that XOR value and count how many bits are set to 1.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428E - CHASE!

The problem statement for Codeforces 103428E - CHASE! is missing from your prompt, so I don’t have the actual rules, inputs, or required output to base an editorial on.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428C - Assign or Multiply

Let $q$ be a primitive $m$th root of unity. For each $i$ with $1 le i le t$, write $$ni = m ai + bi, qquad 0 le bi < m,$$ and set $$N = n1 + cdots + nt, qquad A = a1 + cdots + at, qquad B = b1 + cdots + bt,$$ so that $N = mA + B$.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428A - Goodbye, Ziyin!

The problem statement section is empty, so there isn’t enough information to reconstruct what Codeforces 103428A - “Goodbye, Ziyin!” is asking. An editorial depends completely on the operations, constraints, and output definition.
codeforces competitive-programming Jul 3, 2026
Practice › Codeforces Solutions › The 2021 CCPC Weihai Onsite ›

CF 103428D - Period

We are given a fixed string consisting of lowercase letters. Then we receive many queries; each query temporarily changes one position of the string into a special character , and we must answer a question about the modified string.
codeforces competitive-programming Jul 3, 2026