Codeforces Round 843 (Div. 2)

Solutions for Codeforces Round 843 (Div. 2) (contest 1775). 2/7 problems verified against sample I/O. Difficulty range: 800-2500.

7 items

Codeforces Round 843 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 2/7 | Rating range: 800-2500 | Time: 15m 23s

Problem	Name	Rating	Tags	Solve Time	Verified
A1	Gardener and the Capybaras (easy version)	800	brute-force, constructive-algorithms, implementation	2m 19s	✗
A2	Gardener and the Capybaras (hard version)	900	constructive-algorithms, greedy	1m 44s	✗
B	Gardener and the Array	1300	bitmasks, constructive-algorithms	1m 51s	✓
C	Interesting Sequence	1600	bitmasks, math	3m 21s	✓
D	Friendly Spiders	1800	dfs-and-similar, graphs, math	27s	✗
E	The Human Equation	2100	greedy, implementation	3m 28s	✗
F	Laboratory on Pluto	2500	constructive-algorithms, dp, greedy	2m 13s	✗

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775E - The Human Equation

We are given an array of integers and a peculiar operation that allows us to select any subsequence and adjust its elements in an alternating fashion: either adding 1 to numbers at odd positions and subtracting 1 from numbers at even positions, or the reverse.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775C - Interesting Sequence

We are asked to find the smallest integer $m ge n$ such that the bitwise AND of all numbers from $n$ to $m$ equals a given number $x$. Formally, we want $n & (n+1) & dots & m = x$.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775F - Laboratory on Pluto

This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775A1 - Gardener and the Capybaras (easy version)

This is a Type B (prove inequality) problem, not Type C. The task is to prove that $$frac1{a^3(b+c)}+frac1{b^3(c+a)}+frac1{c^3(a+b)}ge frac32$$ for all positive $a,b,c$ satisfying $abc=1$.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775D - Friendly Spiders

We are given a colony of spiders on Mars, each identified by the number of legs it has. Two spiders are considered friends if the greatest common divisor of their leg counts is greater than one.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775B - Gardener and the Array

We are given an array of integers where each integer is specified by the set of its 1-bits rather than its numeric value. The task is to determine whether there exist two distinct subsequences of the array that produce the same bitwise OR.

Practice › Codeforces Solutions › Codeforces Round 843 (Div. 2) ›

CF 1775A2 - Gardener and the Capybaras (hard version)

The problem gives us a string of letters 'a' and 'b', which represents three capybara names concatenated together.