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Modify points in-place

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Thanks to skius from libera##rust for the idea
This commit is contained in:
Bert Peters
2021-12-13 22:55:14 +01:00
parent 554683bc64
commit b5866b2d8a
1 changed files with 9 additions and 19 deletions
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28
2021/src/day13.rs
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@@ -54,27 +54,19 @@ fn read_input(input: &mut dyn Read) -> (Vec<Coords>, Vec<Fold>) {
parse_input(&input_buffer).finish().unwrap().1 parse_input(&input_buffer).finish().unwrap().1
} }
fn apply_fold(dots: &mut Vec<Coords>, fold: Fold, to_fold: &mut Vec<Coords>) { fn apply_fold(dots: &mut Vec<Coords>, fold: Fold) {
match fold { match fold {
Fold::X(coord) => dots.retain(|&(x, y)| { Fold::X(coord) => dots.iter_mut().for_each(|(x, _)| {
if x < coord { if *x >= coord {
true *x = 2 * coord - *x;
} else {
to_fold.push((2 * coord - x, y));
false
} }
}), }),
Fold::Y(coord) => dots.retain(|&(x, y)| { Fold::Y(coord) => dots.iter_mut().for_each(|(_, y)| {
if y < coord { if *y >= coord {
true *y = 2 * coord - *y;
} else {
to_fold.push((x, 2 * coord - y));
false
} }
}), }),
} }
dots.append(to_fold);
} }
fn print_dots(dots: &[Coords]) -> String { fn print_dots(dots: &[Coords]) -> String {
@@ -98,7 +90,7 @@ fn print_dots(dots: &[Coords]) -> String {
pub fn part1(input: &mut dyn Read) -> String { pub fn part1(input: &mut dyn Read) -> String {
let (mut dots, folds) = read_input(input); let (mut dots, folds) = read_input(input);
apply_fold(&mut dots, folds[0], &mut Vec::new()); apply_fold(&mut dots, folds[0]);
dots.sort_unstable(); dots.sort_unstable();
@@ -108,11 +100,9 @@ pub fn part1(input: &mut dyn Read) -> String {
pub fn part2(input: &mut dyn Read) -> String { pub fn part2(input: &mut dyn Read) -> String {
let (mut dots, folds) = read_input(input); let (mut dots, folds) = read_input(input);
let mut to_fold = Vec::new();
folds folds
.into_iter() .into_iter()
.for_each(|fold| apply_fold(&mut dots, fold, &mut to_fold)); .for_each(|fold| apply_fold(&mut dots, fold));
print_dots(&dots) print_dots(&dots)
} }