The 2021 China Collegiate Programming Contest (Harbin)

12 problems from The 2021 China Collegiate Programming Contest (Harbin) (contest 103447), difficulty -. 10/12 solutions verified against sample I/O.

12 items

The 2021 China Collegiate Programming Contest (Harbin)

Special | 12 problems | 10/12 verified | Difficulty - | 9m 24s

# Problem Rating Tags Accepted Time ✓
A So Many Lucky Strings 45s ✓
B Magical Subsequence 42s
C Colorful Tree 1m 9s ✓
D Math master 44s ✓
E Power and Modulo 40s ✓
F Master Spark 29s
G Damaged Bicycle 59s ✓
H What logic for? 34s ✓
I Power and Zero 50s ✓
J Local Minimum 40s ✓
K Wonder Egg Priority 47s ✓
L Karshilov's Matching Problem 1m 5s ✓
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CF 103447L - Karshilov's Matching Problem

We are given a long digit string and a collection of small digit patterns, each pattern carrying a weight. For any string $S$, we define its value as the sum over all patterns of how many times each pattern appears as a substring inside $S$, multiplied by that pattern’s…
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CF 103447K - Wonder Egg Priority

We are maintaining a sequence of numbers that represents the current “power level” of a collection of eggs. Each egg has an initial value, and over time we repeatedly apply multiplicative updates on subsegments or ask for the sum of a subsegment. There are two operations.
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CF 103447J - Local Minimum

We are given a rectangular grid of numbers. For each cell, we look at all values that lie either in the same row or in the same column as that cell, including the cell itself. Among all those values, we check whether the current cell’s value is the smallest.
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CF 103447D - Math master

We are given a small number of fractions, each represented by a pair of integers $p$ and $q$. The unusual operation allowed is to delete digits from the decimal representations of both numbers, but only in pairs: whenever a digit appears in both numbers, we may choose…
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CF 103447I - Power and Zero

We are given an array of positive integers. The goal is to reduce every value to zero using a sequence of operations. In one operation, we choose a list of indices $B1, B2, dots, Bm$.
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CF 103447G - Damaged Bicycle

We are given a weighted undirected graph representing a campus. Moving along an edge of length $w$ takes time proportional to how you travel: walking always costs $w / t$, while cycling costs $w / r$, with $r ge t$, so cycling is faster.
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CF 103447H - What logic for?

Each query gives two integer sequences and a parameter $k$. The operation allowed is to pick a starting position $a$ and swap two consecutive blocks of length $k$: the segment $S[a..a+k-1]$ is exchanged with $S[a+k..a+2k-1]$.
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CF 103447F - Master Spark

Working
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CF 103447E - Power and Modulo

We are given an array of non-negative integers that is supposed to represent values generated by a hidden modulus process. There exists an unknown positive integer $M$, and the array is expected to match the sequence formed by taking powers of two and reducing them modulo $M$.
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CF 103447A - So Many Lucky Strings

We are given a sequence of strings, and we are allowed to pick any subset of them while preserving their original order. After choosing a subset, we concatenate the selected strings into a single long string.
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CF 103447C - Colorful Tree

We are given a rooted tree where only the leaves matter for the final goal. Every leaf already has a required final color, while internal nodes have no target color at all. Initially, nothing is painted.
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CF 103447B - Magical Subsequence

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