Codeforces Beta Round 60

5 problems from Codeforces Beta Round 60 (contest 65), difficulty 1700-2900. 3/5 solutions verified against sample I/O.

5 items

Codeforces Beta Round 60

Beta | 5 problems | 3/5 verified | Difficulty 1700-2900 | 11m 31s

# Problem Rating Tags Accepted Time ✓
A Harry Potter and Three Spells 1800 implementation, math 2,014 2m 2s ✓
B Harry Potter and the History of Magic 1700 brute-force, greedy, implementation 1,551 2m 33s
C Harry Potter and the Golden Snitch 2100 binary-search, geometry 869 2m 11s ✓
D Harry Potter and the Sorting Hat 2200 brute-force, dfs-and-similar, hashing 480 1m 58s ✓
E Harry Potter and Moving Staircases 2900 dfs-and-similar, implementation 106 2m 47s
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CF 65A - Harry Potter and Three Spells

We have three transformation spells that convert one material into another. The first spell turns a grams of sand into b grams of lead. The second spell turns c grams of lead into d grams of gold. The third spell turns e grams of gold into f grams of sand.
codeforces competitive-programming implementation math May 28, 2026
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CF 65B - Harry Potter and the History of Magic

We are given a sequence of four-digit years. Each year may contain mistakes, but we are allowed to repair it by changing at most one digit. After all repairs, the sequence must become non-decreasing, and every resulting year must stay between 1000 and 2011 inclusive.
codeforces competitive-programming brute-force greedy implementation May 28, 2026
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CF 65C - Harry Potter and the Golden Snitch

The snitch moves along a fixed polyline in 3D space. It starts at the first vertex and travels segment by segment at constant speed vs. Harry starts at another point and can move in any direction at constant speed vp, where vp = vs.
codeforces competitive-programming binary-search geometry May 28, 2026
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CF 65D - Harry Potter and the Sorting Hat

We process students one by one. Each student either has a fixed house, represented by one of the letters G, H, R, S, or has ambiguous ancestry, represented by ?. A fixed student always goes into that house. A ? student behaves differently.
codeforces competitive-programming brute-force dfs-and-similar hashing May 28, 2026
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CF 65E - Harry Potter and Moving Staircases

We are given an undirected multigraph. Floors are vertices, staircases are edges. Harry starts at floor 1 and wants to visit every floor at least once. The graph is dynamic. Between Harry's walks, Ron and Hermione may modify staircases.
codeforces competitive-programming dfs-and-similar implementation May 28, 2026