Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!)

Solutions for Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) (contest 1910). 1/10 problems verified against sample I/O. Difficulty range: 1100-2900.

10 items

Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!)

Type: Kotlin | Problems: 10 | Verified: 1/10 | Rating range: 1100-2900 | Time: 21m 21s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Username	1100	*special, implementation	2m 2s	✗
B	Security Guard	1600	*special, greedy	1m 45s	✗
C	Poisonous Swamp	1600	*special, implementation	2m 14s	✗
D	Remove and Add	1800	*special, greedy	2m 5s	✗
E	Maximum Sum Subarrays	2100	*special, dp	2m 27s	✗
F	Build Railway Stations	2000	*special, greedy, trees	2m 20s	✗
G	Pool Records	2700	*special, greedy	1m 51s	✗
H	Sum of Digits of Sums	2400	*special, binary-search, data-structures	1m 26s	✓
I	Inverse Problem	2700	*special, combinatorics, dp	3m 12s	✗
J	Two Colors	2900	*special	1m 59s	✗

Practice › Codeforces Solutions › Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) ›

CF 1910I - Inverse Problem

We are given a string process that repeatedly deletes any contiguous block of exactly k characters until the string becomes too short to continue. Because deletions are arbitrary, many different final outcomes of length r = n mod k are possible.

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CF 1910J - Two Colors

We are given a weighted tree where every vertex is colored either red or blue. Between any two vertices, the distance is the sum of edge weights along the unique path in the tree. Alongside this structure, we must assign an integer value $vi$ to every vertex.

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CF 1910H - Sum of Digits of Sums

We are given a list of positive integers. For every element in this list, we need to compute a score defined by pairing it with every element in the array, adding the pair, taking the sum of digits of that sum, and accumulating all those values.

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CF 1910G - Pool Records

We are given a sequence of time moments when two swimmers, Alice and Bob, are observed at exactly the same position while moving back and forth on a 50-unit segment.

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CF 1910F - Build Railway Stations

We are given a tree where each edge has a fixed travel cost of 2 hours. We are allowed to pick at most $k$ cities and place railway stations in them. Once stations exist, any edge whose endpoints both have stations becomes cheaper, its cost drops from 2 to 1.

Practice › Codeforces Solutions › Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) ›

CF 1910E - Maximum Sum Subarrays

We are given two arrays, a and b, each of length n. For each index i, we may swap a[i] and b[i] any number of times. After all swaps, we define f(c) as the maximum sum of a contiguous subarray of array c, including the possibility of an empty subarray whose sum is 0.

Practice › Codeforces Solutions › Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) ›

CF 1910D - Remove and Add

We are given an ordered sequence of numbers. We are allowed to delete exactly one element from it, and after that we may choose any subset of the remaining elements and increase each chosen element by exactly one.

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CF 1910C - Poisonous Swamp

We are given a swamp represented as a $2 times n$ grid. In each column, there is exactly one lily pad, marked with an asterisk, and one empty cell, marked with a dot. A frog sits on every lily pad.

Practice › Codeforces Solutions › Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) ›

CF 1910A - Username

We are given a string that is known to be an account identifier formed by taking some valid username and appending a positive integer at the end. The integer part is guaranteed to have no leading zeros, so it behaves like a standard decimal number representation.

Practice › Codeforces Solutions › Kotlin Heroes: Episode 9 (Unrated, T-Shirts + Prizes!) ›

CF 1910B - Security Guard

We are given a log of a system that tracks how many people are inside a building over time. Each character in the string represents an event: a plus means someone enters, and a minus means someone leaves. The system starts the day with zero people inside.