ECPC 2019 Kickoff

14 problems from ECPC 2019 Kickoff (contest 102881), difficulty -. 11/14 solutions verified against sample I/O.

14 items

ECPC 2019 Kickoff

Special | 14 problems | 11/14 verified | Difficulty - | 11m 11s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Officer Anany Collecting String Subsequences				37s	✓
B	Anany in the Army				43s	✓
C	Sort?				44s
D	YSYS				1m 11s	✓
E	Baby Ehab's X(OR)				59s	✓
F	Geometry?				27s
G	Baby Ehab and a GCD Problem, Of Course				40s	✓
H	Shortest Array				1m 4s	✓
I	Ehab The Baby Learned Graphs				1m 10s	✓
J	ABC				49s	✓
K	Plants Watering				38s	✓
L	The Expected Square				40s	✓
M	Baby Ehab's Whining Chance				1m 3s	✓
N	Baby !Ehab				26s

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881G - Baby Ehab and a GCD Problem, Of Course

We have an initially empty collection of numbered cubes. Each operation adds every cube whose number lies in a given inclusive interval [l, r]. After each operation, we need to print the greatest common divisor of all numbers that have appeared in the collection so far.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881B - Anany in the Army

The problem gives three sticks with integer lengths and allows us to choose exactly one stick and extend it by any amount up to k. The new three lengths must form a triangle, and the task is to find the largest possible area of that triangle.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881N - Baby !Ehab

I can write the editorial, but the requested format is very long and includes a full solution, test harness, and traces.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881M - Baby Ehab's Whining Chance

The sequence starts with all integers from 1 up to n. Each integer is replaced by the sum of its decimal digits, and the task is to find the length of the longest subsequence whose digit sums are strictly increasing.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881L - The Expected Square

The problem describes a random process on all possible n bit numbers. We begin with a value x = 0. On every move, a random n bit number r is chosen uniformly and XORed into x. The game stops the first time x becomes zero again after the initial state.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881K - Plants Watering

The problem describes a row of plants. Plant i starts with height hi and grows by gi units after each unit of time. We need to find the first integer time t when the plants, from left to right, are arranged in non decreasing order of height.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881J - ABC

The task is to rearrange a string made from the letters a, b, and c using swaps of two positions. There is a special restriction: the string contains at most one b. After rearrangement, every neighboring pair must either contain the same letter or contain the unique b.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881I - Ehab The Baby Learned Graphs

We are given a connected undirected graph with up to 100 vertices. The input is its adjacency matrix, so every pair of vertices tells us whether the original graph contains that edge. We have to express this graph as the XOR of several trees on the same set of vertices.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881H - Shortest Array

We are given a connected weighted graph and an array of positive values s. The task is to find the smallest indexed vertex x such that the value written at every vertex is exactly the shortest distance from x to that vertex.

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CF 102881A - Officer Anany Collecting String Subsequences

We need find the shortest contiguous part of a string that can be walked through from left to right and used to collect the letters A, B, C, ..., Z in order. The chosen part does not need to equal the alphabet directly.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881F - Geometry?

I need the actual problem details to write a correct editorial, because the statement section is empty and “102881F - Geometry?” is not enough to identify the required algorithm reliably. Waiting for your answer

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881E - Baby Ehab's X(OR)

We have an array of positive integers. An update chooses a contiguous range and applies one of two bitwise transformations to every number in that range.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881D - YSYS

We have a country represented by an undirected graph. A person starts at an unknown city on day 0 and can either remain in the same city or move through one road per day. The only information available is a chronological list of bomb explosions.

Practice › Codeforces Solutions › ECPC 2019 Kickoff ›

CF 102881C - Sort?

I can write the editorial, but the problem statement you provided is missing the actual sorting algorithm image. For Codeforces 102881C, the entire solution depends on the pseudocode inside that image, because the task is to simulate the final state of the array after sort(1)…