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Implement 2023 day 24 part 2

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Bert Peters
2023-12-25 15:00:28 +01:00
parent 5d811a08b6
commit 9b164a4d9d
2 changed files with 83 additions and 2 deletions
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2
2023/Cargo.toml
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@@ -9,7 +9,9 @@ edition = "2021"
aho-corasick = "1.1.2"
anyhow = "1.0.75"
clap = { version = "4.4.8", features = ["derive"] }
linfa-linalg = "0.1.0"
linked-hash-map = "0.5.6"
ndarray = "0.15.6"
nom = "7.1.3"
num-integer = "0.1.45"
rand = "0.8.5"

83
2023/src/day24.rs
View File

@@ -1,3 +1,4 @@
use linfa_linalg::qr::QRInto;
use nom::bytes::complete::tag;
use nom::character::complete::space1;
use nom::combinator::map;
@@ -95,8 +96,81 @@ pub fn part1(input: &[u8]) -> anyhow::Result<String> {
part1_parametrized(input, 200000000000000.0, 400000000000000.0)
}
pub fn part2(_input: &[u8]) -> anyhow::Result<String> {
anyhow::bail!("Not implemented")
pub fn part2(input: &[u8]) -> anyhow::Result<String> {
let hail = parse_input(input, parse_hail)?;
let p0 = hail[0].position.map(|v| v as f64);
let p1 = hail[1].position.map(|v| v as f64);
let p2 = hail[2].position.map(|v| v as f64);
let v0 = hail[0].speed.map(|v| v as f64);
let v1 = hail[1].speed.map(|v| v as f64);
let v2 = hail[2].speed.map(|v| v as f64);
let b = ndarray::array![
[(p0[1] * v0[0] - p1[1] * v1[0]) - (p0[0] * v0[1] - p1[0] * v1[1])],
[(p0[1] * v0[0] - p2[1] * v2[0]) - (p0[0] * v0[1] - p2[0] * v2[1])],
[(p0[2] * v0[0] - p1[2] * v1[0]) - (p0[0] * v0[2] - p1[0] * v1[2])],
[(p0[2] * v0[0] - p2[2] * v2[0]) - (p0[0] * v0[2] - p2[0] * v2[2])],
[(p0[2] * v0[1] - p1[2] * v1[1]) - (p0[1] * v0[2] - p1[1] * v1[2])],
[(p0[2] * v0[1] - p2[2] * v2[1]) - (p0[1] * v0[2] - p2[1] * v2[2])],
];
let a = ndarray::array![
[
v1[1] - v0[1],
v0[0] - v1[0],
0.0,
p0[1] - p1[1],
p1[0] - p0[0],
0.0
],
[
v2[1] - v0[1],
v0[0] - v2[0],
0.0,
p0[1] - p2[1],
p2[0] - p0[0],
0.0
],
[
v1[2] - v0[2],
0.0,
v0[0] - v1[0],
p0[2] - p1[2],
0.0,
p1[0] - p0[0]
],
[
v2[2] - v0[2],
0.0,
v0[0] - v2[0],
p0[2] - p2[2],
0.0,
p2[0] - p0[0]
],
[
0.0,
v1[2] - v0[2],
v0[1] - v1[1],
0.0,
p0[2] - p1[2],
p1[1] - p0[1]
],
[
0.0,
v2[2] - v0[2],
v0[1] - v2[1],
0.0,
p0[2] - p2[2],
p2[1] - p0[1]
],
];
let rock = a.qr_into()?.solve_into(b)?;
Ok((rock[[0, 0]] + rock[[1, 0]] + rock[[2, 0]])
.round()
.to_string())
}
#[cfg(test)]
@@ -109,4 +183,9 @@ mod tests {
fn sample_part1() {
assert_eq!("2", part1_parametrized(SAMPLE, 7.0, 27.0).unwrap());
}
#[test]
fn sample_part2() {
assert_eq!("47", part2(SAMPLE).unwrap());
}
}