Codeforces Global Round 30 (Div. 1 + Div. 2)

9 problems from Codeforces Global Round 30 (Div. 1 + Div. 2) (contest 2164), difficulty 800-3400. 2/9 solutions verified against sample I/O.

9 items

Codeforces Global Round 30 (Div. 1 + Div. 2)

Div. 1+2 | 9 problems | 2/9 verified | Difficulty 800-3400 | 16m 10s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Sequence Game	800	brute-force, sortings	20,816	1m 14s	✓
B	Even Modulo Pair	1000	brute-force, math, number-theory	18,235	1m 39s
C	Dungeon	1400	binary-search, brute-force, data-structures	10,688	2m 2s
D	Copy String	1800	greedy, implementation, strings	4,959	1m 35s
E	Journey	2300	data-structures, dfs-and-similar, dsu	1,578	1m 52s
F1	Chain Prefix Rank (Easy Version)	2600	combinatorics, dfs-and-similar, dp	649	2m 26s	✓
F2	Chain Prefix Rank (Hard Version)	2900	binary-search, combinatorics, data-structures	422	1m 51s
G	Pointless Machine	3300	constructive-algorithms, graphs, interactive	203	1m 53s
H	PalindromePalindrome	3400	data-structures, strings	43	1m 38s

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CF 2164H - PalindromePalindrome

We are given a long base string and many independent queries, each asking about a contiguous segment. For any queried segment, we are interested in all substrings that are palindromes and that appear at least twice inside that segment.

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CF 2164G - Pointless Machine

We are dealing with a hidden tree on $n$ labeled vertices, but we cannot see its edges directly. Instead, we can “probe” the tree using permutations. Each query is a full ordering of the vertices.

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CF 2164F2 - Chain Prefix Rank (Hard Version)

We are given a rooted tree where every vertex has a fixed parent, and thus a fixed ancestor structure. Alongside this tree, each vertex $u$ comes with a target number $au$.

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CF 2164F1 - Chain Prefix Rank (Easy Version)

We are given a rooted tree with $n$ nodes, labeled from $1$ to $n$, with node $1$ as the root. For each node $u$, a number $au$ is specified.

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CF 2164E - Journey

We are given an undirected connected graph with vertices and weighted edges. We start at vertex 1 and must traverse the graph such that every edge is marked at least once, returning to the start.

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CF 2164D - Copy String

We start with a string s and want to turn it into another string t, both of the same length. The only allowed move does not directly edit characters; instead, it rebuilds the entire string at once using a very constrained rule.

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CF 2164C - Dungeon

We are asked to simulate a dungeon scenario where you have a set of swords, each with a damage value, and a set of monsters, each with a life value. You can kill a monster if your sword’s damage is at least equal to the monster’s life.

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CF 2164B - Even Modulo Pair

We are given several test cases. In each one, we receive a strictly increasing list of positive integers. The task is to choose two different elements from this list, call them $x$ and $y$, with the restriction that $x < y$, such that when we divide $y$ by $x$, the remainder…

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CF 2164A - Sequence Game

We are given a sequence of numbers, and we repeatedly compress it until only one value remains. Each operation takes two adjacent elements, removes them, and replaces them with any integer lying between the two original values, inclusive.