New Year and Conference
Filled with optimism, Hyunuk will host a conference about how great this new year will be! The conference will have $n$ lectures. Hyunuk has two […]
ACM
New Year and Castle Construction
Kiwon’s favorite video game is now holding a new year event to motivate the users! The game is about building and defending a castle, which […]
New Year and Social Network
Donghyun’s new social network service (SNS) contains $n$ users numbered $1, 2, \ldots, n$. Internally, their network is a tree graph, so there are $n-1$ direct […]
NEKO’s Maze Game
NEKO#ΦωΦ has just got a new maze game on her PC! The game’s main puzzle is a maze, in the forms of a $2 \times […]
Aroma’s Search
With a new body, our idol Aroma White (or should we call her Kaori Minamiya?) begins to uncover her lost past through the OS space. […]
Chaotic V.
“Everything has been planned out. No more hidden concerns. The condition of Cytus is also perfect. The time right now…… 00:01:12…… It’s time.” The emotion […]
Xenon’s Attack on the Gangs
On another floor of the A.R.C. Markland-N, the young man Simon “Xenon” Jackson, takes a break after finishing his project early (as always). Having a […]
Rin and The Unknown Flower
This is an interactive problem! On a normal day at the hidden office in A.R.C. Markland-N, Rin received an artifact, given to her by the […]
Irreducible Anagrams
Let’s call two strings $s$ and $t$ anagrams of each other if it is possible to rearrange symbols in the string $s$ to get a string, equal […]
Mind Control
You and your $n – 1$ friends have found an array of integers $a_1, a_2, \dots, a_n$. You have decided to share it in the […]
Making Shapes
You are given $n$ pairwise non-collinear two-dimensional vectors. You can make shapes in the two-dimensional plane with these vectors in the following fashion: Start at […]
Coffee Varieties (hard version)
This is the hard version of the problem. You can find the easy version in the Div. 2 contest. Both versions only differ in the […]
Prefix Enlightenment
There are $n$ lamps on a line, numbered from $1$ to $n$. Each one has an initial state off ($0$) or on ($1$). You’re given […]
Cow and Haybales
The USA Construction Operation (USACO) recently ordered Farmer John to arrange a row of $n$ haybale piles on the farm. The $i$-th pile contains $a_i$ haybales. However, […]
Cow and Friend
Bessie has way too many friends because she is everyone’s favorite cow! Her new friend Rabbit is trying to hop over so they can play! […]
Cow and Message
Bessie the cow has just intercepted a text that Farmer John sent to Burger Queen! However, Bessie is sure that there is a secret message […]
Cow and Fields
Bessie is out grazing on the farm, which consists of $n$ fields connected by $m$ bidirectional roads. She is currently at field $1$, and will […]
Cow and Treats
After a successful year of milk production, Farmer John is rewarding his cows with their favorite treat: tasty grass! On the field, there is a […]
Recommendations
VK news recommendation system daily selects interesting publications of one of $n$ disjoint categories for each user. Each publication belongs to exactly one category. For […]
Strange Function
Let’s define the function $f$ of multiset $a$ as the multiset of number of occurences of every number, that is present in $a$. E.g., $f(\{5, […]
