🎄
Advent of Code 2021 Solutions for the 2021 edition of Advent of Code.
This year, I try to do this in Rust
What I learned:
- Day01
- organization of the project
- using the
lib.rs
to expose modules - referencing them in
main.rs
. - Read a file with
fs::read_to_string
, - iterate the lines with
.lines()
. parse().unwrap()
for a quick parsing of the line based on declared type in the function.
- Day02
- I used
split_whitespace
, butsplit_once(" ")
would have been better, because I could unpack the result directly. - If you iter a borrowed vector, you get a double reference for arguments. You can unpack them with
for &(x, y)
to access the value as (here)&str
, otherwise you get&&ref
and you cannot compare those to string literals. Another solution is to usex.as_ref
.
- I used
- Day03
- HashMap default value:
hashmap.get(x).unwrap_or(0)
- HashMap mutating with default value:
hashmap.entry(w).or_insert(0) += 1
- HashMap default value:
- Day04
- Converting a
Vec
into an array withtry_into().unwrap()
.
- Converting a
- Day08
- Regex with the
regex
crate (along withlazy_static
to avoid duplicate compilation of regexes). - HashSet exists.
- Regex with the
- Day09
- Mutating a ref in a recursive function (say
fn func(&mut input)
) can be called internally withfn(input)
,fn(&mut input)
is not necessary.
- Mutating a ref in a recursive function (say
- Day10
- When building in release, integer will overflow with no warnings,
u32
was not giving the right answer,u64
does...
- When building in release, integer will overflow with no warnings,
- Day11
- You can use
get_mut
on anHashMap
to get a mutable reference.
- You can use