Codeforces Round 521 (Div. 3)

7 problems from Codeforces Round 521 (Div. 3) (contest 1077), difficulty 800-2100. 6/7 solutions verified against sample I/O.

7 items

Codeforces Round 521 (Div. 3)

Div. 3 | 7 problems | 6/7 verified | Difficulty 800-2100 | 20m 23s

# Problem Rating Tags Accepted Time ✓
A Frog Jumping 800 math 32,248 1m 58s ✓
B Disturbed People 1000 greedy 20,435 1m 58s ✓
C Good Array 1300 25,584 4m 23s
D Cutting Out 1600 binary-search, sortings 10,474 2m 20s ✓
E Thematic Contests 1800 greedy, sortings 5,092 2m 57s ✓
F1 Pictures with Kittens (easy version) 1900 dp 5,346 2m 1s ✓
F2 Pictures with Kittens (hard version) 2100 data-structures, dp 4,181 4m 46s ✓
Practice › Codeforces Solutions › Codeforces Round 521 (Div. 3) ›

CF 1077F2 - Pictures with Kittens (hard version)

We are given a sequence of pictures arranged in a line, each with a beauty value. We need to choose exactly x of these pictures to repost, but the choice is constrained by a coverage rule: any contiguous block of length at least k must contain at least one chosen picture.
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CF 1077F1 - Pictures with Kittens (easy version)

We are given a line of pictures, each with a value representing its beauty. The task is to select exactly a fixed number of pictures, and among all such selections we want the maximum total beauty.
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CF 1077E - Thematic Contests

We are given a multiset of problems where each problem belongs to a topic. The same topic can appear many times. From this pool, we want to form several contests. Each contest must use only problems from a single topic, so it is homogeneous.
codeforces competitive-programming greedy sortings Jun 15, 2026
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CF 1077D - Cutting Out

We are given a multiset of integers, and we want to construct a pattern array of fixed length $k$. Once we choose this pattern, we repeatedly try to “extract” it from the original multiset: each extraction consumes one occurrence of every value in the pattern, and after…
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Practice › Codeforces Solutions › Codeforces Round 521 (Div. 3) ›

CF 1077C - Good Array

We are given a list of integers, and we want to identify which positions behave “special” under a deletion operation. For each index, we temporarily remove that element and look at the remaining array.
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CF 1077B - Disturbed People

We are given a row of flats, each either having its light on or off. The configuration is a binary array where 1 means lit and 0 means dark.
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Practice › Codeforces Solutions › Codeforces Round 521 (Div. 3) ›

CF 1077A - Frog Jumping

A frog moves along a number line starting from position zero. Its movement is strictly alternating: it first jumps to the right by a fixed distance a, then to the left by b, then right again by a, and so on.
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