Hello 2022

Solutions for Hello 2022 (contest 1621). 2/9 problems verified against sample I/O. Difficulty range: 800-3500.

9 items

Hello 2022

Type: Special | Problems: 9 | Verified: 2/9 | Rating range: 800-3500 | Time: 19m 10s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Stable Arrangement of Rooks	800	constructive-algorithms	6m 15s	✗
B	Integers Shop	1500	data-structures, greedy, implementation	1m 49s	✓
C	Hidden Permutations	1700	dfs-and-similar, interactive, math	1m 40s	✗
D	The Winter Hike	2100	constructive-algorithms, greedy, math	1m 40s	✗
E	New School	2300	binary-search, data-structures, dp	2m 3s	✗
F	Strange Instructions	2700	data-structures, greedy, implementation	1m 37s	✗
G	Weighted Increasing Subsequences	3200	data-structures, dp, math	1m 37s	✗
H	Trains and Airplanes	3500	dfs-and-similar, graphs, shortest-paths	48s	✓
I	Two Sequences	3500	data-structures, hashing, string-suffix-structures	1m 41s	✗

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621I - Two Sequences

We are given an array A of length n and asked to repeatedly apply a complex transformation to it. The transformation, called op, builds a new array from an old one by repeatedly finding the lexicographically smallest subarray of increasing lengths and updating the last…

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621A - Stable Arrangement of Rooks

Ah! That last error is simple: the code tries to use sys.stdin.buffer.read() but forgot to import sys. That’s just a Python module import missing - a small oversight, not a logic error.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621H - Trains and Airplanes

We are given a connected undirected graph with n nodes. Each edge represents either a train or an airplane connection between two cities. Trains have a travel cost of 1, and airplanes have a travel cost of 0.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621G - Weighted Increasing Subsequences

We are given an array of integers and we consider all strictly increasing subsequences formed by choosing indices in increasing order.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621F - Strange Instructions

We are given a binary string that evolves through a sequence of local transformations. Each transformation either compresses adjacent equal bits while earning money, or deletes a zero while paying a cost.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621E - New School

We are asked to assign teachers to groups of students in such a way that each teacher is responsible for at most one group, each group has exactly one teacher, and the teacher’s age is at least the average age of the students in their assigned group.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621D - The Winter Hike

We are given a square grid of size $2n times 2n$. The top-left quadrant, consisting of the first $n$ rows and first $n$ columns, initially contains exactly one friend per cell.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621B - Integers Shop

Each segment in this problem is best thought of as a closed interval on the integer line, paired with a cost. When Vasya chooses a set of segments, he automatically obtains every integer covered by at least one chosen interval, and he pays the sum of their costs.

Practice › Codeforces Solutions › Hello 2022 ›

CF 1621C - Hidden Permutations

We are dealing with two permutations of the same set of indices from 1 to n. One permutation, call it p, is hidden and fixed.