Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2)

Solutions for Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) (contest 2127). 2/9 problems verified against sample I/O. Difficulty range: 800-3500.

9 items

Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2)

Type: Div. 1+2 | Problems: 9 | Verified: 2/9 | Rating range: 800-3500 | Time: 21m 47s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Mix Mex Max	800	constructive-algorithms, greedy, math	3m 30s	✗
B	Hamiiid, Haaamid... Hamid?	1300	games, greedy	2m 6s	✓
C	Trip Shopping	1400	games, greedy, sortings	2m 11s	✗
D	Root was Built by Love, Broken by Destiny	1800	combinatorics, dfs-and-similar, graphs	1m 52s	✗
E	Ancient Tree	2100	constructive-algorithms, data-structures, dfs-and-similar	2m 24s	✗
F	Hamed and AghaBalaSar	2800	brute-force, combinatorics, dp	3m 4s	✗
G1	Inter Active (Easy Version)	3400	binary-search, constructive-algorithms, interactive	1m 39s	✗
G2	Inter Active (Hard Version)	3500	binary-search, bitmasks, constructive-algorithms	3m 19s	✗
H	23 Rises Again	3100	brute-force, dfs-and-similar, dp	1m 42s	✓

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127G2 - Inter Active (Hard Version)

We are dealing with a hidden structure, a permutation of size $n$, where every position points to exactly one value and no value repeats. There is an additional restriction that no element stays in its original position, so the permutation contains no fixed points.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127F - Hamed and AghaBalaSar

You’re not dealing with a “small bug anymore” - the issue is that the last solution implicitly solved a different problem (monotone feasibility) than the one your samples are testing. We can prove that directly from the third failing case.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127G1 - Inter Active (Easy Version)

We are given a hidden permutation of size $n$, with the additional promise that no element stays in its own position. So every index points to a different value, and every value appears exactly once. We cannot see this permutation directly.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127E - Ancient Tree

We are given a rooted tree with weighted vertices, where each vertex either has a fixed color between 1 and k or a missing color represented by 0. The goal is to assign colors to all uncolored vertices to minimize the total weight of "cutie" vertices.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127D - Root was Built by Love, Broken by Destiny

We are given a connected undirected graph of n houses and m bridges. Each bridge must connect one house on the northern side of a river to one house on the southern side.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127A - Mix Mex Max

At this point the failures are not coming from “a small bug in transitions” or “a corner case in logic”. They come from a much simpler fact: The code you are running is not implementing the problem you are testing. We can prove this directly from your sample.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127C - Trip Shopping

We are given two arrays of integers, a and b, representing prices of items in two categories. The game consists of k rounds. In each round, Ali selects two indices, and Bahamin can rearrange the four numbers at those indices arbitrarily, even swapping elements between arrays.

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127B - Hamiiid, Haaamid... Hamid?

We are given a one-dimensional grid of length n, with some cells containing walls and others empty. Hamid is standing on one empty cell, and every day two things happen: first Mani places a wall on an empty cell not currently occupied by Hamid, then Hamid chooses a direction…

Practice › Codeforces Solutions › Atto Round 1 (Codeforces Round 1041, Div. 1 + Div. 2) ›

CF 2127H - 23 Rises Again

We are given an undirected, connected graph with up to 30 vertices, where each vertex belongs to at most 5 simple cycles. A simple cycle here is a closed path where each vertex has exactly two neighbors.