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day8: refactor and cleanup

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This commit is contained in:
Keenan Tims
2024-12-07 22:49:57 -08:00
parent 47e40942e2
commit 622877843e
1 changed files with 47 additions and 58 deletions
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105
8/src/main.rs
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@@ -39,81 +39,70 @@ fn main() {
struct AntennaMap { struct AntennaMap {
map: Grid<u8>, map: Grid<u8>,
antinodes: Grid<u8>,
} }
impl<T: BufRead> From<Lines<T>> for AntennaMap { impl<T: BufRead> From<Lines<T>> for AntennaMap {
fn from(input: Lines<T>) -> Self { fn from(input: Lines<T>) -> Self {
let map = Grid::from(input); Self { map: Grid::from(input) }
let width = map.width(); }
let height = map.height(); }
Self {
map, impl AntennaMap {
antinodes: Grid::with_shape(width, height, b'.'), fn find_antinodes(&self, start: usize, reps: Option<usize>) -> Grid<bool> {
let mut antinodes = Grid::with_shape(self.map.width(), self.map.height(), false);
// find the unique frequencies in a dumb way
// NOTE: The dumb way is faster than the slightly-smarter ways I tried
let freq_set: HashSet<&u8> = HashSet::from_iter(self.map.data.iter().filter(|c| **c != b'.'));
// for each unique frequency, get all the pairs' positions
for freq in freq_set {
for pair in self
.map
.data
.iter()
.enumerate()
.filter(|(_, c)| *c == freq)
.map(|(i, _)| self.map.coord(i as i64).unwrap())
.permutations(2)
{
// permutations generates both pairs, ie. ((1,2),(2,1)) and ((2,1),(1,2)) so we don't need
// to consider the 'negative' side of the line, which will be generated by the other pair
let (a, b) = (pair[0], pair[1]);
let offset = (a.0 - b.0, a.1 - b.1);
for i in (start..).map_while(|i| {
if Some(i - start) != reps {
Some(i as i64)
} else {
None
}
}) {
let node_pos = (a.0 + i * offset.0, a.1 + i * offset.1);
if !antinodes.set(node_pos.0, node_pos.1, true) {
// left the grid
break;
}
}
}
} }
antinodes
} }
} }
// PROBLEM 1 solution // PROBLEM 1 solution
fn problem1<T: BufRead>(input: Lines<T>) -> u64 { fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
let mut map = AntennaMap::from(input); let map = AntennaMap::from(input);
// find the unique frequencies in a dumb way let antinodes = map.find_antinodes(1, Some(1));
let freq_set: HashSet<&u8> = HashSet::from_iter(map.map.data.iter().filter(|c| **c != b'.')); antinodes.count(true) as u64
// for each unique frequency, get all the pairs' positions
for freq in freq_set {
let coords = map
.map
.data
.iter()
.enumerate()
.filter(|(_, c)| *c == freq)
.map(|(i, _)| map.map.coord(i as i64).unwrap())
.collect_vec();
for pair in coords.iter().permutations(2).collect_vec() {
let (a, b) = (pair[0], pair[1]);
let node_pos = (a.0 + a.0 - b.0, a.1 + a.1 - b.1);
map.antinodes.set(node_pos.0, node_pos.1, b'#');
}
}
map.antinodes.count(b'#') as u64
} }
// PROBLEM 2 solution // PROBLEM 2 solution
fn problem2<T: BufRead>(input: Lines<T>) -> u64 { fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
let mut map = AntennaMap::from(input); let map = AntennaMap::from(input);
// find the unique frequencies in a dumb way let antinodes = map.find_antinodes(0, None);
let freq_set: HashSet<&u8> = HashSet::from_iter(map.map.data.iter().filter(|c| **c != b'.')); antinodes.count(true) as u64
// for each unique frequency, get all the pairs' positions
for freq in freq_set {
let coords = map
.map
.data
.iter()
.enumerate()
.filter(|(_, c)| *c == freq)
.map(|(i, _)| map.map.coord(i as i64).unwrap())
.collect_vec();
for pair in coords.iter().permutations(2).collect_vec() {
let (a, b) = (pair[0], pair[1]);
let offset = (a.0 - b.0, a.1 - b.1);
let mut i = 0;
loop {
let node_pos = (a.0 + i * offset.0, a.1 + i * offset.1);
if !map.antinodes.set(node_pos.0, node_pos.1, b'#') {
break;
}
i += 1;
}
}
}
map.antinodes.count(b'#') as u64
} }
#[cfg(test)] #[cfg(test)]