Codeforces Round 809 (Div. 2)

Solutions for Codeforces Round 809 (Div. 2) (contest 1706). 2/6 problems verified against sample I/O. Difficulty range: 800-2400.

6 items

Codeforces Round 809 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 2/6 | Rating range: 800-2400 | Time: 13m 42s

Problem Name Rating Tags Solve Time Verified
A Another String Minimization Problem 800 2-sat, constructive-algorithms, greedy 1m 52s ✓
B Making Towers 1100 dp, greedy, math 3m 3s ✗
C Qpwoeirut And The City 1400 dp, flows, greedy 1m 51s ✗
D1 Chopping Carrots (Easy Version) 1700 binary-search, brute-force, constructive-algorithms 2m 39s ✗
D2 Chopping Carrots (Hard Version) 2400 brute-force, constructive-algorithms, data-structures 2m 4s ✓
E Qpwoeirut and Vertices 2300 binary-search, data-structures, dfs-and-similar 2m 13s ✗
Practice › Codeforces Solutions › Codeforces Round 809 (Div. 2) ›

CF 1706E - Qpwoeirut and Vertices

We are given a connected undirected graph with $n$ vertices and $m$ edges. Each edge is numbered from 1 to $m$, and we are asked to process $q$ queries.
codeforces competitive-programming binary-search data-structures dfs-and-similar divide-and-conquer dsu greedy trees Jun 9, 2026
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CF 1706D1 - Chopping Carrots (Easy Version)

Two constructions are proposed for generating a random variable $X$ with a nontrivial distribution on $[-1,1]$. The first maps a single uniform deviate through a trigonometric transformation.
codeforces competitive-programming binary-search brute-force constructive-algorithms greedy number-theory Jun 9, 2026
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CF 1706D2 - Chopping Carrots (Hard Version)

We are given a sorted array of integers representing carrot sizes and a limit k. Our goal is to assign to each carrot a number of cuts, represented by integers pi between 1 and k. Cutting a carrot ai into pi pieces produces a piece size of floor(ai / pi).
codeforces competitive-programming brute-force constructive-algorithms data-structures dp greedy math number-theory two-pointers Jun 9, 2026
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CF 1706B - Making Towers

We are given a sequence of n blocks, each with a color from 1 to n. We need to place them one by one on a 2D grid. The first block always starts at (0, 0).
codeforces competitive-programming dp greedy math Jun 9, 2026
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CF 1706A - Another String Minimization Problem

We are asked to construct a string of length m, initially filled with the letter 'B', by performing n operations defined by a sequence a1, a2, ..., an.
codeforces competitive-programming 2-sat constructive-algorithms greedy string-suffix-structures strings Jun 9, 2026
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CF 1706C - Qpwoeirut And The City

We are given a row of buildings, each with a certain number of floors. A building is considered "cool" if it is strictly taller than both its immediate neighbors. The first and last buildings cannot be cool because they do not have two neighbors.
codeforces competitive-programming dp flows greedy implementation Jun 9, 2026