A — Captcha
Author: m7a1g5i8k8a1r4p0
Just print the number of circles in the image. There are 7 if you include the circles in i and ?.
B — Right or Wrong?
Author: m7a1g5i8k8a1r4p0
The title implies that you should check if the 3 numbers are "right" or not. You can do this by checking that $$$a$$$, $$$b$$$, and $$$c$$$ form the side lengths of a right triangle, with $$$c$$$ as the hypotenuse.
C — New Sorting Algorithm
Author: ChiMasterBing
You are sorting a permutation, so all you have to do is print out the integers from $$$1$$$ to $$$n$$$, inclusive. The time constraints are very lax for this. Though you should be careful of the memory limit. If you read the second line entirely, you will probably get MLE. If you form a large string and then print it out, you will probably get MLE.
D — Subset Sums
Author: m7a1g5i8k8a1r4p0
Clearly, solving this problem as is is too hard. Is there anything that you are missing here?
Try pressing Ctrl+A to highlight all the text.
If you highlight the space below "Notes," you will see the following equations: 
If you plot these functions in Desmos, you will realize that $$$a$$$ is still a variable. By setting $$$a$$$ to $$$0$$$, $$$1$$$, and $$$2$$$, you will see the equations spell out XOR.
This signifies that the question is actually asking about how many subset XOR sums equal $$$k$$$. This can be done in $$$O(n\log \max{a_i})$$$
E — Gemini
Author: m7a1g5i8k8a1r4p0
Castor and Pollux are the twin stars of the Gemini constellation, but it seems like we can only see Castor...
To solve Castor's problem, all even numbers must be put into separate sets. It can be shown that the required number of sets is always equal to $$$\lfloor\frac{n}{2}\rfloor$$$. You can do this by pairing 1 2, 3 4, 5 6, etc. for even values of $$$n$$$. If $$$n$$$ is odd, you can instead do n-2 n-1 n for the last set.
After submitting, you will receive a verdict of Хороший! Now help solve Pollux's problem! This signifies that you should now look at Castor's partner, Pollux, since he also has a problem to solve. This can be done by switching your language to Russian.
To solve Pollux's problem, just write any sieve to print out the primes up to $$$n$$$.
At this point, you will probably get a verdict of Oops, now Castor is getting a Wrong Answer on his end. This means you should somehow solve both of their problems at the same time. (This is where the weird output format comes into play)
To solve both of their problems, first print out all of the primes in one set to satisfy Pollux's problem. Then, try to complete the original construction from Castor's problem, but skip over any instance where you have already placed a number into the set of primes. Also, place $$$1$$$ into any set other than the first set.
F — Something's Fishy
Author: m7a1g5i8k8a1r4p0
This problem has the exact same name as a previous UTPC April Fools problem, and it also has some cursed numbers in it, though this time it relates to a different fish.
First, we should solve for the variables.
$$$X = 2206$$$
$$$a = 14$$$, this should include the one that just happened before this contest
$$$r = 3$$$, no the answer is not $$$2$$$, are you an AI model?
$$$c = 37$$$, a reference to this video
$$$l = 1$$$, this is Legendre's Constant $$$j = 31$$$, July always has $$$31$$$ days
$$$h = 11$$$, there are $$$9$$$ Heegner numbers, and $$$11$$$ is the median of all of them
$$$m = 777$$$, Matikanefukukitaru has a skill that activates with $$$777$$$m left in the race, she is also closely related to luck in general (and so is $$$777$$$)
Note that the $$$|$$$ operator denotes concatenation.
So, $$$Y = 143\cdot (37+10)\cdot 131\cdot 11777 \mod 10^9+7$$$, which gives us $$$Y=369071357$$$.
Now, what can we do with $$$2206$$$ and $$$369071357$$$?
If you pay attention to the flavor text, it mentions something about the ICPC Championship in Asia, which is on Codeforces, and is quite recent. If you click into the contest and look at the URL, the ID of the contest is also $$$2206$$$, so what about $$$369071357$$$?
If you look at submission $$$369071357$$$ from the 2026 Asia Pacific Championship, you will get this submission.
Looking at the code, it is a compile error, which is very suspicious, and there is a massive template, which is not immediately suspicious. That is, until you realize that some parts of the template are quite suspect, such as #define N number. When would that ever be useful? If you take all of the suspicious parts and read the capital letters in order, they will spell ANSHIDDEN, which should tell you that the answer is HIDDEN.
You can diff the submission against a previous submission to see what got changed.
G — Forgot where I took this pic
Author: zmonster8
Play Geoguessr. Any coordinate within 110 meters will be accepted. The real location is at 22.2763644 114.1568149. You can also try to triangulate the spot since the checker will tell you how far you are.
H — Fill in the Blanks
Author: m7a1g5i8k8a1r4p0
It seems like increasing the index decreases the value, and decreasing the index increases the value. Also, the first element is "bad" for some reason.
You should not interpret $$$a_i$$$ as the $$$i$$$th element of a list. Rather, you should think of $$$a_i$$$ as some value $$$a$$$ in base $$$i$$$. This matches the ideas from the previous hint, and base 1 is not well defined. So the problem is simply to convert $$$a$$$ from base $$$i$$$ to base $$$j$$$. The constraints imply that the true value of $$$a$$$ does not exceed $$$10^{18}$$$. $$$j$$$ is always at most $$$10$$$, so the answer will always be numeric.
I — Networking Problem
Author: 25huangvictoria
If you submit anything, you will get a verdict of Connection request pending. Have you checked the 6th floor? Checking the 6th floor of the GDC will lead you to a QR code that will link to a LinkedIn profile. Connecting will give back an automated response telling you that the answer is: I have added Victoria Huang on LinkedIn!. (Please don't spam)
J — Guess the Number!
Author: m7a1g5i8k8a1r4p0
At first, this seems impossible, until you realize that you have $$$4!=24$$$ queries, not $$$4$$$. For $$$1\le x\le 10^6$$$, binary searching on the answer will need $$$20$$$ queries, so $$$24$$$ is more than enough.
K — Guessing Game
Author: WalrusRamen21
After looking at the clues, you should realize that the answers cannot really be words. Each clue should solve to a year instead, but years have $$$4$$$ digits, and this game of Wordle has $$$5$$$ blanks...
The hint says that The present is built upon the results of the past. This implies that you should look at the "results of the past," specifically the past Wordle answers.
You should get:
1. 1646 $$$\rightarrow$$$ QUILT
2. 1612 $$$\rightarrow$$$ CLAMP
3. 1578 $$$\rightarrow$$$ FORUM
4. 1596 $$$\rightarrow$$$ MOTEL
So, the final answer should be MAUVE.
L — MST
Author: m7a1g5i8k8a1r4p0
This would require some code if this were an actual MST problem, but of course, it is not. Note that the question does not specify that the graph must be connected, so we can just choose to take none of the edges (also, all edges have positive weight). This means the answer is just always 0.
M — META
Author: m7a1g5i8k8a1r4p0
This metapuzzle is in the style of a puzzlehunt.
Alternative medicine focused on specific points on the body using one's hands (11)
Something you "pass in", or an altercation (8)
Something you can do with a car, or something you can "catch" (5)
Stereotypically found in cartoons when someone is running very fast (4 5)
Guard, or someone who refrains from disclosing the location of their favorite restaurant (10)
Certain type of lounge for smoking (6)
Symbol representing ejection in a match (3 4)
Type of competition used in the Olympics that allows for second chances (9)
Common type of appetizer for those who cannot choose just one item (7)
Common action in Minecraft, or a type of fish (5)
Something found in grandparents' homes, or something found behind certain windows (9)
Alice's location (10)
You should solve all of the clues first.
The parentheses indicate the enumeration of the answer to a clue. So "fish" would be (4) and "magic carp" would be (5 4)
Also, after solving some of the clues, you will probably realize that all of the answers are in alphabetical order.
ACUPRESSURE
ARGUMENT, you pass in arguments in code, and get into arguments as an altercation
DRIFT, you can drift in a car, and you can catch someone's drift
DUST CLOUD
GATEKEEPER, this is modern parlance
HOOKAH, search up "hookah lounge"
RED CARD
REPECHAGE, this is used primarily in Olympics wrestling
SAMPLER
SMELT, furnaces smelt in Minecraft, smelt is also a fish: https://en.wikipedia.org/wiki/Smelt_(fish)
WALLPAPER, wallpaper is found in older homes, and it is also what is behind windows (or tabs) on a computer
WONDERLAND
"Undirected acyclic connected graph" just means "tree," so this puzzle should be about trees somehow. There is also mention of "trim[ming]" the trees.
If we "trim" some of the answers, we can see some trees show up, though they might be anagrammed. As an example, trimming WALLPAPER gives us LPAPE. Anagramming this gives us APPLE.
ACUPRESSURE $$$\rightarrow$$$ SPRUCE
ARGUMENT $$$\rightarrow$$$ GUM
DRIFT $$$\rightarrow$$$ FIR
DUST CLOUD $$$\rightarrow$$$ LOCUST
GATEKEEPER $$$\rightarrow$$$ TEAK
HOOKAH $$$\rightarrow$$$ OAK
RED CARD $$$\rightarrow$$$ CEDAR
REPECHAGE $$$\rightarrow$$$ PEACH
SAMPLER $$$\rightarrow$$$ MAPLE
SMELT $$$\rightarrow$$$ ELM
WALLPAPER $$$\rightarrow$$$ APPLE
WONDERLAND $$$\rightarrow$$$ ALDER
Now that we have a list of trees, we should consider what the 1. [5] -> 8 stuff means. Usually, [5] indicates that we extract the 5th letter from some word/phrase. But the second row wants us to extract the 5th letter from GUM, which doesn't exist. So, let's sort the trees in alphabetical order, then perform the extraction.
ALDER $$$\rightarrow$$$ R
APPLE $$$\rightarrow$$$ E
CEDAR $$$\rightarrow$$$ ED
ELM $$$\rightarrow$$$ E
FIR $$$\rightarrow$$$ FR
GUM $$$\rightarrow$$$ U
LOCUST $$$\rightarrow$$$ S
MAPLE $$$\rightarrow$$$ PE
OAK $$$\rightarrow$$$ O
PEACH $$$\rightarrow$$$ H
SPRUCE $$$\rightarrow$$$ UC
TEAK $$$\rightarrow$$$ T
The letters we have so far don't make any sense, so let's use the information to the right of the arrows (the 8 from 1. [5] -> 8). Looking at all of these numbers, we see that they form a permutation of the first 16 positive integers, so let's use those numbers as indices into a 16-letter phrase. Then, we can rearrange the letters we have so far to uncover USETHEPRUFERCODE ("use the prufer code", which relates to trees!). This matches up with the final answer being 4 words. Now, what is the proper capitalization?
Take a look at:
use
the
prufer
code
Notice how the letters UTPC line up along the left. This indicates that we should only capitalize those letters, for the final answer of:
Use
The
Prufer
Code
If you used ü instead of u, that is also accepted.
