Advent of Code on Hieu Phay

Advent of Code 2021 in Julia – Day 18: Snailfish

Sun, 19 Dec 2021 00:00:00 +0000

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This one was quite difficult. It took me 2 days to solve this one.

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You descend into the ocean trench and encounter some snailfish. They say they saw the sleigh keys! They’ll even tell you which direction the keys went if you help one of the smaller snailfish with his math homework.

Advent of Code 2021 in Julia – Day 17: Trick Shot

Fri, 17 Dec 2021 00:00:00 +0000

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An easy puzzle for today’s. I wonder if there is a more clever solution…

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You finally decode the Elves’ message. HI, the message says. You continue searching for the sleigh keys.

Ahead of you is what appears to be a large ocean trench. Could the keys have fallen into it? You’d better send a probe to investigate.

Advent of Code 2021 in Julia – Day 16: Packet Decoder

Thu, 16 Dec 2021 00:00:00 +0000

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I can feel the difficulty ramping up in the last few days. For the second part of the puzzle, I had to utilized Julia’s meta-programming capacity. It’s the first time I touched the meta-programming section in the Julia documentation. Fortunately my code worked fine this time, and I can still keep up with solving the puzzles during the same day they’re released.

Advent of Code 2021 in Julia – Day 15: Chiton

Wed, 15 Dec 2021 00:00:00 +0000

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The one today is difficult but fun! It provided a very nice example for dynamic programming. I would probably revisit this puzzle again if I have the time.

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You’ve almost reached the exit of the cave, but the walls are getting closer together. Your submarine can barely still fit, though; the main problem is that the walls of the cave are covered in chitons, and it would be best not to bump any of them.

Advent of Code 2021 in Julia – Day 14: Extended Polymerization

Tue, 14 Dec 2021 00:00:00 +0000

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The puzzle today is akin to that in day 6: A naive, recursive implementation works for part 1, but is too intensive for part 2, and requires a different approach.

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The incredible pressures at this depth are starting to put a strain on your submarine. The submarine has polymerization equipment that would produce suitable materials to reinforce the submarine, and the nearby volcanically-active caves should even have the necessary input elements in sufficient quantities.

Advent of Code 2021 in Julia – Day 13: Transparent Origami

Mon, 13 Dec 2021 00:00:00 +0000

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Alright! We’re halfway through! The puzzle today is easier than the last, as a “monday” puzzle would, but it is fun nontheless. The puzzle format break out from the tradition of “compute in this method and return this number.” To solve for the puzzle today, you actually have to visualize to see the output.

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You reach another volcanically active part of the cave. It would be nice if you could do some kind of thermal imaging so you could tell ahead of time which caves are too hot to safely enter.

Advent of Code 2021 in Julia – Day 12: Passage Pathing

Sun, 12 Dec 2021 00:00:00 +0000

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The puzzle today competely wrecked me! I spent like three hours on this one.

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With your submarine’s subterranean subsystems subsisting suboptimally, the only way you’re getting out of this cave anytime soon is by finding a path yourself. Not just a path - the only way to know if you’ve found the best path is to find all of them.

Advent of Code 2021 in Julia – Day 11: Dumbo Octopus

Sat, 11 Dec 2021 00:00:00 +0000

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I like the concept behind the puzzle today. It’s about autonomous synchronization. It happens in the nature all the time, see this simulation.

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You enter a large cavern full of rare bioluminescent dumbo octopuses! They seem to not like the Christmas lights on your submarine, so you turn them off for now.

Advent of Code 2021 in Julia – Day 10: Syntax Scoring

Fri, 10 Dec 2021 00:00:00 +0000

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The puzzle today was sort of interesting, because my solution is quite unique. Because this puzzle is inspired by real-life bracket pairing problems, people typically implement an algorithm along that line. But I was completely oblivious of those algorithm, so I had another approach! My attempt works fine for this puzzle, but i’s probably useless if I want to expand my solution to a full-fledge parser.

Advent of Code 2021 in Julia – Day 9: Smoke Basin

Thu, 09 Dec 2021 00:00:00 +0000

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I feel like it’s almost everyday that I can say something like: “Oooh, I thought it was going to be easy, but then it’s not!” Well… That’s certainly the case for today.

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These caves seem to be lava tubes. Parts are even still volcanically active; small hydrothermal vents release smoke into the caves that slowly settles like rain.

Advent of Code 2021 in Julia – Day 8: Seven Segment Search

Wed, 08 Dec 2021 00:00:00 +0000

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This one is not too hard, but a brain teaser nonetheless. The key thing I learnt today is that strings in Julia are arrays of characters, so you can use set operators to check for things like "ab" ⊆ "cab", which should return true.

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You barely reach the safety of the cave when the whale smashes into the cave mouth, collapsing it. Sensors indicate another exit to this cave at a much greater depth, so you have no choice but to press on.

Advent of Code 2021 in Julia – Day 7: The Treachery of Whales

Tue, 07 Dec 2021 00:00:00 +0000

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Today’s challenge is quite simple. Blame Julia for having a good set of defaults.

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A giant whale has decided your submarine is its next meal, and it’s much faster than you are. There’s nowhere to run!

Suddenly, a swarm of crabs (each in its own tiny submarine - it’s too deep for them otherwise) zooms in to rescue you! They seem to be preparing to blast a hole in the ocean floor; sensors indicate a massive underground cave system just beyond where they’re aiming!

Advent of Code 2021 in Julia – Day 6: Lanternfish

Mon, 06 Dec 2021 00:00:00 +0000

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The problem today is a bit of a breather. (Puzzles are easier on weekdays.) Still, I fell right into their trap! But it’s alright. In fact, I really like this puzzle, because I had tons of fun toying with its visualization!

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The sea floor is getting steeper. Maybe the sleigh keys got carried this way?

Advent of Code 2021 in Julia – Day 5: Hydrothermal Venture

Sun, 05 Dec 2021 00:00:00 +0000

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I thought the challenge today would be easy, but in the end I spent too much time on it. Around halfway through I realized that I forgot to offset the index, because Julia indexes begin at 1 instead of 0. On the other hand, I learnt how slurping and splatting with ... works, which provide shorthand for “unwrapping” arrays, to be used inside functions.

Advent of Code 2021 in Julia – Day 4: Giant Squid

Sat, 04 Dec 2021 00:00:00 +0000

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The challenge today is a bigger one. You basically have to write a Bingo verifier. It’s the first one that I had to resort to importing another library (DelimitedFiles), but I would argue that because DelimitedFiles is bundled within Julia installation, it’s not a cheat ;) The library did not play any role in the meat of the puzzle anyway.

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You’re already almost 1.5km (almost a mile) below the surface of the ocean, already so deep that you can’t see any sunlight. What you can see, however, is a giant squid that has attached itself to the outside of your submarine.

Advent of Code 2021 in Julia – Day 3: Binary Diagnostic

Fri, 03 Dec 2021 00:00:00 +0000

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It’s getting interesting! Today’s problem got me stucked for a while – mainly because I didn’t read the question closely enough. For this excercise I work with matrices, which Julia handles really well.

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The submarine has been making some odd creaking noises, so you ask it to produce a diagnostic report just in case.

Advent of Code 2021 in Julia – Day 2: Dive!

Thu, 02 Dec 2021 00:00:00 +0000

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Now, you need to figure out how to pilot this thing.

It seems like the submarine can take a series of commands like forward 1, down 2, or up 3:

forward X increases the horizontal position by X units.
down X increases the depth by X units.
up X decreases the depth by X units.

Note that since you’re on a submarine, down and up affect your depth, and so they have the opposite result of what you might expect.

Advent of Code 2021 in Julia – Day 1: Sonar Sweep

Wed, 01 Dec 2021 00:00:00 +0000

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This is my attempt to the Advent of Code challenge. It is a yearly event where you solve coding puzzles every day from December 1st until December 25th. The puzzles are not too hard or technical, and you can use any language you like to solve them – a perfect opportunity for me to learn a new language. And who can turn down some fun puzzles anyway?