ACM

Hilbert’s Hotel

2020 VietMX 0

Hilbert’s Hotel is a very unusual hotel since the number of rooms is infinite! In fact, there is exactly one room for every integer, including zero […]

Monopole Magnets

2020 VietMX 0

A monopole magnet is a magnet that only has one pole, either north or south. They don’t actually exist since real magnets have two poles, […]

Quantifier Question

2020 VietMX 0

Logical quantifiers are very useful tools for expressing claims about a set. For this problem, let’s focus on the set of real numbers specifically. The set […]

Résumé Review

2020 VietMX 0

Uh oh! Applications to tech companies are due soon, and you’ve been procrastinating by doing contests instead! (Let’s pretend for now that it is actually […]

Piet’s Palette

2020 VietMX 0

Piet Mondrian is an artist most famous for his minimalist works, consisting only of the four colors red, yellow, blue, and white. Most people attribute […]

Train Tracks

2020 VietMX 0

That’s right. I’m a Purdue student, and I shamelessly wrote a problem about trains. There are $n$ stations and $m$ trains. The stations are connected […]

Orac and LCM

2020 VietMX 1

For the multiset of positive integers $s=\{s_1,s_2,\dots,s_k\}$, define the Greatest Common Divisor (GCD) and Least Common Multiple (LCM) of $s$ as follow: $\gcd(s)$ is the […]

Orac and Game of Life

2020 VietMX 0

Please notice the unusual memory limit of this problem. Orac likes games. Recently he came up with the new game, “Game of Life”. You should […]

Orac and Medians

2020 VietMX 0

Slime has a sequence of positive integers $a_1, a_2, \ldots, a_n$. In one operation Orac can choose an arbitrary subsegment $[l \ldots r]$ of this […]