Codeforces Round 1012 (Div. 2)

Solutions for Codeforces Round 1012 (Div. 2) (contest 2090). 2/8 problems verified against sample I/O. Difficulty range: 800-3100.

8 items

Codeforces Round 1012 (Div. 2)

Type: Div. 2 | Problems: 8 | Verified: 2/8 | Rating range: 800-3100 | Time: 12m 30s

Problem Name Rating Tags Solve Time Verified
A Treasure Hunt 800 implementation, math 1m 26s ✓
B Pushing Balls 1000 brute-force, dp, implementation 1m 48s ✓
C Dining Hall 1700 data-structures, greedy, implementation 1m 40s ✗
D Simple Permutation 1700 constructive-algorithms, number-theory 1m 23s ✗
E1 Canteen (Easy Version) 1900 data-structures, math, two-pointers 1m 34s ✗
E2 Canteen (Hard Version) 2300 binary-search, data-structures, greedy 1m 44s ✗
F1 Key of Like (Easy Version) 2200 combinatorics, dp, math 1m 31s ✗
F2 Key of Like (Hard Version) 3100 dp, math, probabilities 1m 24s ✗
Practice › Codeforces Solutions › Codeforces Round 1012 (Div. 2) ›

CF 2090F2 - Key of Like (Hard Version)

We are asked to simulate a sequential key-and-lock game among n players. There are l locks, each with a unique corresponding key, and k counterfeit keys that do not open any lock.
codeforces competitive-programming dp math probabilities Jun 9, 2026
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CF 2090E2 - Canteen (Hard Version)

We are given two sequences of integers, a and b, both of length n. Each element of a represents some resource or quantity that we want to reduce to zero, and each element of b represents a capacity or counter-resource.
codeforces competitive-programming binary-search data-structures greedy Jun 9, 2026
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CF 2090F1 - Key of Like (Easy Version)

We are asked to calculate the expected number of successful key-lock matches for each participant in a turn-based game. There are $n$ members taking turns sequentially, $l$ locks, and exactly $l$ keys (since $k = 0$ in this easy version). Each key opens exactly one lock.
codeforces competitive-programming combinatorics dp math probabilities Jun 9, 2026
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CF 2090E1 - Canteen (Easy Version)

We are given two sequences of integers, a and b, both of length n. The goal is to reduce all elements of a to zero by performing a repeated operation called a round.
codeforces competitive-programming data-structures math two-pointers Jun 9, 2026
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CF 2090B - Pushing Balls

We are given the final occupancy pattern of a grid after some sequence of ball insertions. A ball can be pushed either from the left side of a row or from the top side of a column. The ball travels forward until it reaches a cell. If that cell is empty, it stays there.
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Practice › Codeforces Solutions › Codeforces Round 1012 (Div. 2) ›

CF 2090C - Dining Hall

The dining hall is an infinite grid of cells. Some of these cells are grouped into tables, each table occupying a 2×2 square located at coordinates of the form $(3x+1,3y+1)$ through $(3x+2,3y+2)$, and all other cells are corridors.
codeforces competitive-programming data-structures greedy implementation sortings Jun 9, 2026
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CF 2090D - Simple Permutation

We are asked to construct a permutation of the first $n$ positive integers such that a sequence derived from it has many prime numbers. Specifically, for a permutation $p1, p2, dots, pn$, we define $ci = lceil frac{p1 + p2 + dots + pi}{i} rceil$.
codeforces competitive-programming constructive-algorithms number-theory Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 1012 (Div. 2) ›

CF 2090A - Treasure Hunt

We are asked to determine who will dig up a buried treasure first between two people, Little B and Little K. The treasure is buried at a fractional depth a.5 meters, which is key: it means the threshold is always .5 meters beyond the integer a.
codeforces competitive-programming implementation math Jun 8, 2026