By UTPC_Admin, history, 4 weeks ago,

Hope you enjoyed our contest! The editorial is below:

A — Skipping Songs

Author: sg2themax

Solution

B — 6th heaven

Author: blueberryJam

Solution

C — A Noteworthy Debut

Author: mwen

Solution

D — Counting Records

Author: Daveeed

Solution

E — Is It Vinyl?

Author: jxin31415

Solution

F — Lost in the Album Store

Author: isaac18b

Solution

G — Making Records

Author: DylanSmith

Solution

H — Prefix Tower

Authors: nwx, Daveeed

Solution

I — Record Compression

Author: zekigurbuz

Solution

J — Record The Record Record

Author: tn757

Solution

K — Sample Heat

Author: fishy15

Solution

L — Two Pizzas

Author: DylanSmith

Solution
• +16

 » 4 weeks ago, # |   0 what is generalized pigeonhole principle? you mentioned it but didn't provide any further references.
•  » » 4 weeks ago, # ^ |   0 The base pigeonhole principle states that if we have $n$ objects and $m$ boxes where $n > m$, then at least one of the boxes has more than one item. The generalization is that at least one box has $\lfloor n / m \rfloor$ items for any value of $n$ and $m$.
 » 4 weeks ago, # | ← Rev. 2 →   0 I think there's a typo in the solution for H. It should be x-i+k-1 choose k-1. Or x-i+k-1 choose x-i
•  » » 4 weeks ago, # ^ |   +8 Hi, great catch! We had written this formula with $i$ being 0-indexed, as it was in our code. The formula you gave is correct when $i$ is 1-indexed, which would be consistent with the rest of the solution.
 » 4 weeks ago, # |   0 A solution that doesn't involve hasing for K is using eertree. You only add to the answer when you create a new node on the tree