The 15th Chinese Northeast Collegiate Programming Contest

13 problems from The 15th Chinese Northeast Collegiate Programming Contest (contest 103145), difficulty -. 12/13 solutions verified against sample I/O.

13 items

The 15th Chinese Northeast Collegiate Programming Contest

Special | 13 problems | 12/13 verified | Difficulty - | 13m 22s

# Problem Rating Tags Accepted Time ✓
A Matrix 2m 28s
B Cypher 1m 4s ✓
C Vertex Deletion 1m 12s ✓
D Lowbit 53s ✓
E Easy Math Problem 1m 5s ✓
F Permutation 50s ✓
G Ball 57s ✓
H Loneliness 52s ✓
I Takeaway 43s ✓
J Transform 52s ✓
K City 48s ✓
L k-th Smallest Common Substring 48s ✓
M Master of Shuangpin 50s ✓
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CF 103145A - Matrix

Let κt(N) be the leading parameter in the degree-$t$ combinatorial representation of $N$, so that κt(N) is the unique integer $nt$ satisfying $$binom{nt}{t} le N < binom{nt+1}{t}.
codeforces competitive-programming Jul 3, 2026
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CF 103145I - Takeaway

We are given a fixed menu with seven possible dish types, each type having a known price. For each test case, Kanari selects several dishes, and the input lists which dish types he ordered. The total cost of the order is simply the sum of the corresponding dish prices.
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CF 103145G - Ball

We are given a slope with a fixed number of grooves arranged from bottom to top. Each ball is thrown into some groove, and then it follows a deterministic rule: it tries to occupy its starting groove, but if that groove is already filled, it keeps sliding downward until it…
codeforces competitive-programming Jul 3, 2026
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CF 103145D - Lowbit

We are maintaining an array of integers that changes over time under two kinds of operations. One operation modifies a whole segment of the array by repeatedly adding a special value derived from each element itself, and the other asks for the sum of a segment.
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CF 103145M - Master of Shuangpin

We are given multiple lines, each line is a sentence written in pinyin syllables separated by spaces. Each syllable represents a spoken Chinese sound and must be converted into a two-keystroke Shuangpin representation.
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CF 103145L - k-th Smallest Common Substring

We are given several strings over lowercase letters, and we care about substrings that appear in every one of them. A substring is defined by choosing a contiguous segment inside a string.
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CF 103145K - City

We are given a weighted undirected graph where each edge represents a road between two cities, and each road has a strength value. A global attack parameter $x$ removes every road whose strength is strictly less than $x$.
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CF 103145J - Transform

We are given a fixed line in three-dimensional space, defined by the origin and a point $(A, B, C)$. This line acts as a rotation axis. For each test case, we also receive a point $(x, y, z)$ and an angle $r$.
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CF 103145H - Loneliness

We are working on an $n times n$ grid, where the journey always starts at the top-left cell $(1,1)$ and the goal is to reach the bottom-right cell $(n,n)$.
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CF 103145F - Permutation

We are maintaining a permutation that changes over time, and we must support both structural modifications and queries efficiently. Initially, we are given a permutation of the integers from 1 to n.
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CF 103145B - Cypher

We are simulating a simplified Enigma-style cipher machine. The machine transforms a stream of characters, but the transformation depends heavily on a changing internal state that evolves after every key press. The machine has three layers.
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CF 103145E - Easy Math Problem

We are given a positive integer $p$ for each test case. The task is not to directly compute a function of $p$, but to construct a number $k$ satisfying two simultaneous conditions. First, $k$ must be a multiple of $p$, and it must not exceed $2 cdot 10^{18}$.
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CF 103145C - Vertex Deletion

We are given a tree for each test case, and we choose an arbitrary subset of vertices to delete. After deleting those vertices, the remaining vertices still form a forest, since we are only removing nodes from a tree.
codeforces competitive-programming Jul 3, 2026