Codeforces Round 867 (Div. 3)

Solutions for Codeforces Round 867 (Div. 3) (contest 1822). 5/8 problems verified against sample I/O. Difficulty range: 800-2200.

8 items

Codeforces Round 867 (Div. 3)

Type: Div. 3 | Problems: 8 | Verified: 5/8 | Rating range: 800-2200 | Time: 12m 49s

Problem	Name	Rating	Tags	Solve Time	Verified
A	TubeTube Feed	800	brute-force, implementation	1m 11s	✓
B	Karina and Array	800	greedy, math, sortings	1m 8s	✓
C	Bun Lover	800	math	3m 49s	✗
D	Super-Permutation	1200	constructive-algorithms, math	1m 17s	✓
E	Making Anti-Palindromes	1600	greedy, math, strings	1m 23s	✓
F	Gardening Friends	1700	brute-force, dfs-and-similar, dp	1m 14s	✓
G1	Magic Triples (Easy Version)	1700	brute-force, data-structures, math	1m 27s	✗
G2	Magic Triples (Hard Version)	2200	brute-force, data-structures, math	1m 20s	✗

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822G2 - Magic Triples (Hard Version)

We are asked to count the number of triples of indices in an array where each triple is "magic" according to a multiplicative pattern. Specifically, a triple $(i, j, k)$ is magic if $aj$ is some integer multiple $b$ of $ai$ and $ak$ is the same multiple $b$ of $aj$.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822G1 - Magic Triples (Easy Version)

We are given a sequence of integers and asked to count the number of triples of indices $(i, j, k)$ such that each index is distinct and there exists a positive integer $b$ where multiplying the value at $i$ by $b$ gives the value at $j$, and multiplying the value at $j$ by…

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822C - Bun Lover

Each person contributes one of three things: A fixed seat request consumes exactly one seat and pins structure. A -1 person can always be used to extend a segment outward from the current left boundary.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822F - Gardening Friends

We are given a tree rooted at vertex 1, where every edge has the same length. The “cost” of the tree is simply how far the farthest vertex is from the current root. Because all edges have identical weight, this cost is just the height of the tree times the edge length.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822E - Making Anti-Palindromes

We are given a string consisting of lowercase English letters, and we want to transform it into an anti-palindrome using the minimum number of character swaps.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822D - Super-Permutation

We are given a sequence of integers from 1 to n arranged in some order, and we interpret it as a permutation. From this permutation, we construct a running sum array where each position stores the prefix sum of the permutation, reduced modulo n.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822A - TubeTube Feed

The feed can be thought of as a linear list of videos, each with two attributes: how long it takes to watch and how enjoyable it is. Mushroom Filippov starts at the first video and can move rightwards through the list, spending one second per step to skip to the next item.

Practice › Codeforces Solutions › Codeforces Round 867 (Div. 3) ›

CF 1822B - Karina and Array

We are given an array of integers and we are allowed to delete any subset of elements while preserving the relative order of what remains.