April Fools Day Contest 2019

Solutions for April Fools Day Contest 2019 (contest 1145). 7/7 problems verified against sample I/O. Difficulty range: -.

7 items

April Fools Day Contest 2019

Type: April Fools | Problems: 7 | Verified: 7/7 | Rating range: - | Time: 11m 54s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Thanos Sort	-	*special, implementation	1m 23s	✓
B	Kanban Numbers	-	*special, brute-force	1m 36s	✓
C	Mystery Circuit	-	bitmasks, brute-force	1m 52s	✓
D	Pigeon d'Or	-	*special, implementation	1m 39s	✓
E	Fourier Doodles	-	-	1m 14s	✓
F	Neat Words	-	*special	3m 11s	✓
G	AI Takeover	-	*special, interactive	59s	✓

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CF 1145F - Neat Words

We are given a single string of uppercase letters with length between 1 and 10. The task is to determine whether this string is "neat." A neat word, in this context, is defined as one where no letter appears more than once at even positions or more than once at odd positions.

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CF 1145G - AI Takeover

This is an interactive game against a fixed but unknown opponent program. The opponent chooses one deterministic strategy at the beginning of the test and sticks to it for all 20 rounds.

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CF 1145D - Pigeon d'Or

We are given a small array of integers, each between 1 and 32, and we are asked to find a certain integer that represents the maximum number of consecutive elements that satisfy a bitwise property.

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CF 1145E - Fourier Doodles

We are given a small supervised learning task disguised as a programming problem. There are 50 grayscale images indexed from 1 to 50. For the first 20 images, we are given binary labels indicating whether each image is considered a “Fourier doodle” or not.

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CF 1145C - Mystery Circuit

We are given a single integer a between 0 and 15. This integer represents a configuration of a simple 4-bit circuit, where each bit can be either 0 or 1. The task is to compute an output integer based on a mysterious internal rule of the circuit.

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CF 1145B - Kanban Numbers

We are asked to determine whether a given number can be represented as the sum of any number of integers equal to 4 or 7. The input is a single integer $a$ between 1 and 99, and the output is either "YES" if such a representation exists, or "NO" otherwise.

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CF 1145A - Thanos Sort

We start with an array whose length is a power of two. The allowed operation is very unusual: whenever the current array is not sorted in non-decreasing order, we may delete either its left half or its right half. After that, we repeat the same process on the remaining half.