Articles tagged #advent-of-code
Day 9 (Advent of Code 2020)
3 min
Day 9’s problem statement is convoluted - the “ah maybe that’s why I don’t usually do Advent of Code” kind of convoluted, but let’s give it a go anyway.
So, we have a series of numbers, like so:
35
20
15
25
47
40
62
55
65
95
102
117
150
182
127
219
299
277
309
576
And uh the first N numbers are a “preamble” and every number that comes after that must be the sum of any two of the numbers that come before it.
Day 8 (Advent of Code 2020)
6 min
Time for another Advent of Code 2020 problem!
That one sounds like it’s going to be fun. Our input is pretty much assembly, like this:
nop +0
acc +1
jmp +4
acc +3
jmp -3
acc -99
acc +1
jmp -4
acc +6
So, the first thing we’re going to do is write down some types.
There’s more than one way to approach this problem, but let’s go with this:
#[derive(Debug, Clone, Copy)]
enum InstructionKind {
Nop,
Acc,
Jmp,
}
#[derive(Debug, Clone, Copy)]
struct Instruction {
kind: InstructionKind,
operand: isize,
}
type Program = Vec<Instruction>;
Day 7 (Advent of Code 2020)
12 min
Another day, another Advent of Code 2020 problem.
That one seems fun! For some nerdy values of fun.
Our input is a set of rules:
light red bags contain 1 bright white bag, 2 muted yellow bags.
dark orange bags contain 3 bright white bags, 4 muted yellow bags.
bright white bags contain 1 shiny gold bag.
muted yellow bags contain 2 shiny gold bags, 9 faded blue bags.
shiny gold bags contain 1 dark olive bag, 2 vibrant plum bags.
dark olive bags contain 3 faded blue bags, 4 dotted black bags.
vibrant plum bags contain 5 faded blue bags, 6 dotted black bags.
faded blue bags contain no other bags.
dotted black bags contain no other bags.
Day 6 (Advent of Code 2020)
8 min
The end of Advent of Code 2020 is fast approaching, and we’re nowhere near done. Time to do Day 6!
The problem statement here is a little contrived, as uh, as the days that came before it, but that won’t stop us.
Basically, the input looks like this:
abc
a
b
c
ab
ac
a
a
a
a
b
Each line represents one person, and “groups of persons” are separated by blank lines.
Day 5 (Advent of Code 2020)
6 min
Time for another day of Advent of Code 2020.
For Day 5, we’re going to have to do…
Let me guess: more parsing?
Correct!
So there’s an airline that uses binary space partitioning when referring to seats - there’s 128 rows and 8 columns. The first 7 characters are either F (Front, for the lower half) and B (back, for the upper half), and the last 3 are L (Left, for the lower half) or R (Right, for the upper half).
Day 4 (Advent of Code 2020)
7 min
It’s time for Day 4 of the Advent of Code 2020!
Now, I’ve already had a look at the problem statement, at least for part 1, and I’m not particularly excited.
But it will allow me to underline some of the points I’ve recently been *trying to make about types and correctness.
Ah, yes, the novel.
The problem is to parse passports, with fields like these:
Day 3 (Advent of Code 2020)
9 min
Hello all, and welcome back to Advent of Code 2020, featuring Cool Bear.
Hey y’all!
Let’s get right to it.
The problem statement for Day 3 is as follows: we’re given a map, that looks like this:
..##.......
#...#...#..
.#....#..#.
..#.#...#.#
.#...##..#.
..#.##.....
.#.#.#....#
.#........#
#.##...#...
#...##....#
.#..#...#.#
And we imagine that it repeats infinitely to the right, like so:
Day 2 (Advent of Code 2020)
10 min
Day 2, Day 2! Woo!
The Advent of Code 2020, Day 2 problem talks about passwords. Sounds familiar.
Basically, our input looks like this:
1-3 a: abcde
1-3 b: cdefg
2-9 c: ccccccccc
Each line contains a “password policy” and a “password”. For the first line, the policy is that the password must contain between 1 and 3 (inclusive) times the letter “a”.
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