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day14: some silly and not super effective performance optimizations

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This commit is contained in:
Keenan Tims
2023-12-14 01:57:06 -08:00
parent 7926475a56
commit 78fb884c03
1 changed files with 87 additions and 83 deletions
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170
14/src/main.rs
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@@ -31,51 +31,57 @@ fn main() {
#[derive(Debug)]
struct Platform {
rows: Vec<Vec<char>>,
width: usize,
height: usize,
}
impl<T: BufRead> From<Lines<T>> for Platform {
fn from(lines: Lines<T>) -> Self {
let rows: Vec<Vec<char>> = lines.map(|line| line.unwrap().chars().collect()).collect();
let width = rows[0].len();
let height = rows.len();
Self {
rows: lines.map(|line| line.unwrap().chars().collect()).collect(),
rows,
width,
height,
}
}
}
enum Direction {
North,
South,
East,
West,
}
#[derive(Debug, PartialEq)]
enum Axis {
Rows,
Columns,
}
impl Direction {
fn reverse_direction(&self) -> bool {
match self {
Direction::North | Direction::West => false,
Direction::South | Direction::East => true,
}
}
fn axis(&self) -> Axis {
match self {
Direction::North | Direction::South => Axis::Columns,
Direction::East | Direction::West => Axis::Rows,
}
}
struct North;
struct South;
struct East;
struct West;
trait Direction {
const REVERSED: bool;
const AXIS: Axis;
}
impl Direction for North {
const REVERSED: bool = false;
const AXIS: Axis = Axis::Columns;
}
impl Direction for South {
const REVERSED: bool = true;
const AXIS: Axis = Axis::Columns;
}
impl Direction for East {
const REVERSED: bool = true;
const AXIS: Axis = Axis::Rows;
}
impl Direction for West {
const REVERSED: bool = false;
const AXIS: Axis = Axis::Rows;
}
impl<'a> Platform {
fn width(&self) -> usize {
self.rows[0].len()
}
fn height(&self) -> usize {
self.col(0).len()
}
fn col(&self, col: usize) -> Vec<char> {
self.rows.iter().map(|row| row[col]).collect()
}
@@ -84,97 +90,94 @@ impl<'a> Platform {
self.rows[row_idx][idx] = col[row_idx];
}
}
fn roll(&mut self, dir: &Direction) {
match dir.axis() {
fn roll<T: Direction>(&mut self) {
match T::AXIS {
Axis::Columns => {
for idx in 0..self.width() {
self.roll_one(idx, dir)
for idx in 0..self.width {
let new = self.roll_one::<T>(idx);
self.replace_col(idx, new);
}
}
Axis::Rows => {
for idx in 0..self.height() {
self.roll_one(idx, dir)
for idx in 0..self.height {
let new = self.roll_one::<T>(idx);
self.rows[idx].copy_from_slice(new.as_slice());
}
}
}
}
fn roll_rock_at(old: &mut Vec<char>, inner_idx: usize, dir: &Direction) {
fn roll_rock_at<T: Direction>(old: &mut Vec<char>, inner_idx: usize) {
// Find the first # rock or the edge of the map, we can't look beyond this for a resting position
match dir.reverse_direction() {
true => {
let upper_limit = (inner_idx..old.len())
.find(|c| old[*c] == '#')
.unwrap_or(old.len());
if T::REVERSED {
// The furthest possible resting position is the first # below us, or the edge of the map
let upper_limit = (inner_idx..old.len() - 1)
.find(|c| old[*c] == '#')
.unwrap_or(old.len());
if let Some(empty_pos) = (inner_idx..upper_limit).filter(|i| old[*i] == '.').last()
{
old.swap(inner_idx, empty_pos);
}
// We will roll to the position of the furthest '.' before the upper limit
if let Some(empty_pos) = (inner_idx..upper_limit).rev().find(|i| old[*i] == '.') {
old.swap(inner_idx, empty_pos);
}
false => {
// Find the first # rock or the edge of the map, we can't look beyond this for a resting position
let lower_limit = (0..inner_idx).rev().find(|c| old[*c] == '#').unwrap_or(0);
} else {
// the furthest possible resting position is the first # above us, or the edge
let lower_limit = (0..inner_idx).rev().find(|c| old[*c] == '#').unwrap_or(0);
if let Some(empty_pos) = (lower_limit..inner_idx)
.rev()
.filter(|i| old[*i] == '.')
.last()
{
old.swap(inner_idx, empty_pos);
}
// We will roll to the position of the furthest '.' before the lower limit
if let Some(empty_pos) = (lower_limit..inner_idx).find(|i| old[*i] == '.') {
old.swap(inner_idx, empty_pos);
}
}
}
fn roll_one(&mut self, idx: usize, dir: &Direction) {
let mut old = match dir.axis() {
fn roll_one<T: Direction>(&mut self, idx: usize) -> Vec<char> {
let mut old = match T::AXIS {
Axis::Columns => self.col(idx),
Axis::Rows => self.rows[idx].clone(),
};
let idx_iter: Either<_, _> = match dir.reverse_direction() {
let idx_iter: Either<_, _> = match T::REVERSED {
true => Either::Left((0..old.len()).rev()),
false => Either::Right(0..old.len()),
};
let end_idx = if T::REVERSED { old.len() } else { 0 };
for inner_idx in idx_iter {
match old[inner_idx] {
'.' | '#' => continue,
'O' if dir.reverse_direction() && inner_idx == old.len() => continue,
'O' if !dir.reverse_direction() && inner_idx == 0 => continue,
'O' => Self::roll_rock_at(&mut old, inner_idx, dir),
'O' if inner_idx == end_idx => continue,
'O' => Self::roll_rock_at::<T>(&mut old, inner_idx),
_ => panic!("invalid character"),
}
}
match dir.axis() {
Axis::Columns => self.replace_col(idx, old),
Axis::Rows => self.rows[idx] = old,
old
}
fn score<T: Direction>(&self) -> u64 {
match T::AXIS {
Axis::Columns => self.score_columns::<T>(),
Axis::Rows => self.score_rows::<T>(),
}
}
fn score(&self, dir: &Direction) -> u64 {
match dir.axis() {
Axis::Columns => self.score_columns(dir),
Axis::Rows => self.score_rows(dir),
}
}
fn row_or_column_score(&self, idx: usize, dir: &Direction) -> usize {
if dir.reverse_direction() {
fn row_or_column_score<T: Direction>(&self, idx: usize) -> usize {
if T::REVERSED {
idx + 1
} else {
self.rows.len() - idx
match T::AXIS {
Axis::Rows => self.width - idx,
Axis::Columns => self.height - idx,
}
}
}
fn score_columns(&self, dir: &Direction) -> u64 {
(0..self.height())
fn score_columns<T: Direction>(&self) -> u64 {
(0..self.height)
.map(|row| {
self.rows[row].iter().filter(|c| **c == 'O').count()
* self.row_or_column_score(row, dir)
* self.row_or_column_score::<T>(row)
})
.sum::<usize>() as u64
}
fn roll_cycle(&mut self) {
self.roll(&Direction::North);
self.roll(&Direction::West);
self.roll(&Direction::South);
self.roll(&Direction::East);
self.roll::<North>();
self.roll::<West>();
self.roll::<South>();
self.roll::<East>();
}
// find the first loop, return the iteration count when we first saw it and when we saw it again
@@ -190,7 +193,7 @@ impl<'a> Platform {
}
}
}
fn score_rows(&self, dir: &Direction) -> u64 {
fn score_rows<T: Direction>(&self) -> u64 {
unimplemented!()
}
}
@@ -211,8 +214,8 @@ impl Display for Platform {
fn problem1<T: BufRead>(input: Lines<T>) -> u64 {
let mut p = Platform::from(input);
p.roll(&Direction::North);
p.score(&Direction::North)
p.roll::<North>();
p.score::<North>()
}
// PROBLEM 2 solution
@@ -223,11 +226,12 @@ fn problem2<T: BufRead>(input: Lines<T>) -> u64 {
let loop_length = first_loop.1 - first_loop.0;
let cycles_to_skip = ((ITERATIONS - first_loop.0) / loop_length) * loop_length;
let iterations_remaining = ITERATIONS - first_loop.0 - cycles_to_skip;
for _ in 0..iterations_remaining {
p.roll_cycle();
}
p.score(&Direction::North)
p.score::<North>()
}
#[cfg(test)]