Refact.ai Match 1 (Codeforces Round 985)

Solutions for Refact.ai Match 1 (Codeforces Round 985) (contest 2029). 1/9 problems verified against sample I/O. Difficulty range: 800-3500.

9 items

Refact.ai Match 1 (Codeforces Round 985)

Type: Special | Problems: 9 | Verified: 1/9 | Rating range: 800-3500 | Time: 18m 21s

Problem Name Rating Tags Solve Time Verified
A Set 800 greedy, math 1m 27s ✓
B Replacement 1100 constructive-algorithms, games, strings 1m 37s ✗
C New Rating 1700 binary-search, data-structures, dp 3m 19s ✗
D Cool Graph 1900 constructive-algorithms, data-structures, dfs-and-similar 1m 37s ✗
E Common Generator 2100 brute-force, constructive-algorithms, math 3m 22s ✗
F Palindrome Everywhere 2500 constructive-algorithms, graphs, greedy 1m 44s ✗
G Balanced Problem 3000 data-structures, dp 1m 46s ✗
H Message Spread 3500 bitmasks, brute-force, combinatorics 1m 33s ✗
I Variance Challenge 3400 flows, graphs, greedy 1m 56s ✗
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CF 2029I - Variance Challenge

We are given an integer array and a fixed value $k$. We are allowed to perform an operation that selects a contiguous segment and adds $k$ to every element inside it.
codeforces competitive-programming flows graphs greedy Jun 8, 2026
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CF 2029H - Message Spread

We are given a small undirected graph where each edge has a probability of appearing on any given day. Initially, only vertex 1 knows a message.
codeforces competitive-programming bitmasks brute-force combinatorics dp Jun 8, 2026
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CF 2029G - Balanced Problem

We are asked to maximize a weighted sum over an array of integers that starts as all zeros. The array has length $n$ and receives $m$ initial operations, each of which increases a prefix or suffix of the array by 1.
codeforces competitive-programming data-structures dp Jun 8, 2026
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CF 2029E - Common Generator

We are asked to find a number $x ge 2$ such that every number in a given array $a$ can be generated from $x$ using a special additive rule. The rule allows us to repeatedly add to $x$ one of its divisors that is at least 2, until we reach the target number.
codeforces competitive-programming brute-force constructive-algorithms math number-theory Jun 8, 2026
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CF 2029F - Palindrome Everywhere

We are given a cycle graph with $n$ vertices labeled $0$ to $n-1$. Each edge in the cycle has a color, either red or blue.
codeforces competitive-programming constructive-algorithms graphs greedy Jun 8, 2026
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CF 2029C - New Rating

Ah, now I see the subtle mistake. The previous logic assumed that putting the maximum first and subtracting each element from the maximum works, but that is not correct for the actual score definition: the score is $$sum{i=1}^n (ci - bi)$$ where $ci$ is the prefix maximum up…
codeforces competitive-programming binary-search data-structures dp greedy Jun 8, 2026
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CF 2029D - Cool Graph

We are given a simple undirected graph with $n$ vertices and $m$ edges. The graph can be arbitrary but contains no self-loops or multiple edges. We are allowed to perform a "triangle flip" operation on any three distinct vertices $a$, $b$, $c$.
codeforces competitive-programming constructive-algorithms data-structures dfs-and-similar dsu graphs greedy trees Jun 8, 2026
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CF 2029B - Replacement

We are given a binary string s of length n and another binary string r of length n-1. The problem describes a game where we repeatedly shorten s by replacing any adjacent pair of differing bits with the next character in r. On each turn, we must pick an index k such that s[k] !
codeforces competitive-programming constructive-algorithms games strings Jun 8, 2026
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CF 2029A - Set

We are asked to consider a contiguous set of integers $S$ from $l$ to $r$ and repeatedly remove numbers from $S$ according to a simple rule. A number $x$ can only be removed if there are at least $k$ multiples of $x$ in $S$, counting $x$ itself.
codeforces competitive-programming greedy math Jun 8, 2026