Codeforces Round 870 (Div. 2)

Solutions for Codeforces Round 870 (Div. 2) (contest 1826). 4/6 problems verified against sample I/O. Difficulty range: 1100-2800.

6 items

Codeforces Round 870 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 1100-2800 | Time: 11m 7s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Trust Nobody	1200	brute-force, greedy, implementation	1m 13s	✓
B	Lunatic Never Content	1100	math, number-theory	5m 1s	✗
C	Dreaming of Freedom	1300	greedy, math, number-theory	1m 28s	✓
D	Running Miles	1700	brute-force, dp, greedy	1m 1s	✓
E	Walk the Runway	2400	bitmasks, brute-force, data-structures	1m 3s	✓
F	Fading into Fog	2800	geometry, interactive, math	1m 21s	✗

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CF 1826B - Lunatic Never Content

I have carefully examined the problem and the previous attempts. The algorithm itself - iterating over all subarrays, keeping a running currentmin and currentmax, and adding currentmax - currentmin - is correct for the easy version of the problem.

Practice › Codeforces Solutions › Codeforces Round 870 (Div. 2) ›

CF 1826F - Fading into Fog

We are asked to find a set of hidden points on a 2D plane using queries that return projections of all points onto a line of our choice. Each query gives us the locations of these projections along the line, with slight precision errors.

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CF 1826E - Walk the Runway

We are given a sequence of runway shows across multiple cities, each with its own ranking of models. There are n models and m cities. Each model has a profit value, and each city gives a rating to each model.

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CF 1826D - Running Miles

We are given a linear street with n sights, each at a specific mile marker from the start. Each sight has an associated beauty score.

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CF 1826C - Dreaming of Freedom

We have a group of n programmers who are repeatedly voting to choose a single favorite among m algorithms. Each round, every programmer casts a vote for one of the remaining options.

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CF 1826A - Trust Nobody

We are given a group of people where each person makes a claim about the minimum number of liars in the group. Each person either always tells the truth or always lies. Our task is to decide whether these claims are consistent and, if so, to determine a possible number of liars.