Educational Codeforces Round 184 (Rated for Div. 2)

7 problems from Educational Codeforces Round 184 (Rated for Div. 2) (contest 2169), difficulty 900-2700. 3/7 solutions verified against sample I/O.

7 items

Educational Codeforces Round 184 (Rated for Div. 2)

Div. 2 | 7 problems | 3/7 verified | Difficulty 900-2700 | 13m 34s

# Problem Rating Tags Accepted Time ✓
A Alice and Bob 900 greedy, implementation 19,035 1m 54s
B Drifting Away 1100 greedy, implementation 16,093 2m 4s
C Range Operation 1300 dp, greedy, math 12,656 1m 38s ✓
D1 Removal of a Sequence (Easy Version) 1500 binary-search, implementation, math 8,534 1m 10s ✓
D2 Removal of a Sequence (Hard Version) 2100 binary-search, divide-and-conquer, greedy 2,269 2m 22s
E Points Selection 2400 dp, greedy 1,041 1m 49s ✓
F Subsequence Problem 2700 combinatorics, dp, fft 333 2m 37s
Practice › Codeforces Solutions › Educational Codeforces Round 184 (Rated for Div. 2) ›

CF 2169F - Subsequence Problem

We are asked to count arrays of length $n$ over the integers from 1 to $m$ that are “perfect” with respect to $k$ given sets of numbers. Each set defines the allowable value for a position in a hypothetical “beautiful” array of length $k$.
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CF 2169D2 - Removal of a Sequence (Hard Version)

We are given an infinite sequence of natural numbers starting from 1. Polycarp performs a special removal operation exactly $x$ times. Each operation removes all numbers in positions that are multiples of $y$ in the current sequence.
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CF 2169E - Points Selection

We are asked to model a two-player game on a set of points in the plane, where each point has a cost. Alice removes some points with the goal of maximizing a total score, and Bob then draws the smallest axis-aligned rectangle containing all remaining points to minimize the score.
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CF 2169D1 - Removal of a Sequence (Easy Version)

We start with an infinite sequence of natural numbers, effectively thinking of it as the array 1, 2, 3, 4, .... The process repeatedly removes elements based on a fixed step size y: every time we apply an operation, we delete the elements sitting at positions y, 2y, 3y, ...
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CF 2169B - Drifting Away

We are given a one-dimensional river represented as a string of cells. Each cell has one of three behaviors: it can push Monocarp left, push him right, or do nothing. Monocarp chooses a starting cell and then moves step by step in discrete time.
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CF 2169A - Alice and Bob

Each test case gives a sorted list of marble values and a fixed integer chosen by Alice. Bob must pick his own integer, and then every marble independently awards its point to whoever is closer to that marble’s value, with Alice winning ties.
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CF 2169C - Range Operation

We are given an array of integers and allowed to perform a single operation at most once: choose a contiguous subarray and replace all its elements with the sum of its 1-based endpoints.
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