Codeforces Beta Round 47

Solutions for Codeforces Beta Round 47 (contest 50). 4/5 problems verified against sample I/O. Difficulty range: 800-2300.

5 items

Codeforces Beta Round 47

Type: Beta | Problems: 5 | Verified: 4/5 | Rating range: 800-2300 | Time: 6m 55s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Domino piling	800	greedy, math	1m 5s	✓
B	Choosing Symbol Pairs	1500	strings	1m 15s	✓
C	Happy Farm 5	2000	geometry	55s	✓
D	Bombing	2100	binary-search, dp, probabilities	1m 42s	✗
E	Square Equation Roots	2300	math	1m 58s	✓

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CF 50A - Domino piling

We are asked to place as many standard dominoes as possible on a rectangular board of size _M_ by _N_. Each domino covers exactly two adjacent squares, and dominoes cannot overlap or extend outside the board.

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CF 50B - Choosing Symbol Pairs

We are given a string of characters consisting of lowercase letters and digits. The task is to count the number of ordered pairs of positions in the string where the characters at those positions are identical.

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CF 50C - Happy Farm 5

We have a set of points on a 2D plane representing cows, each with integer coordinates. Vasya, the shepherd, must walk a closed path around all the cows in such a way that every cow lies strictly inside the path. The goal is to minimize the number of moves needed.

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CF 50D - Bombing

We are given a set of enemy objects, each at a fixed 2D coordinate, and a fixed strike point. The objective is to determine the minimum impact radius of a nuclear warhead such that the probability of failing to deactivate at least K of these objects is at most ε per mils.

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CF 50E - Square Equation Roots

We are asked to count all distinct real roots of quadratic equations of the form , where ranges from 1 to and ranges from 1 to . Each pair defines one quadratic. The output is the total number of distinct real roots across all these quadratics.