115 lines
2.6 KiB
Rust
115 lines
2.6 KiB
Rust
#![warn(clippy::pedantic)]
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use std::{
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convert::Infallible,
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io::{stdin, BufRead},
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str::FromStr,
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};
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use vector2d::Vector2D;
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#[derive(Copy, Clone, Debug)]
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struct Line {
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start: Vector2D<usize>,
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end: Vector2D<usize>,
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}
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impl Line {
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pub fn is_straight(&self) -> bool {
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self.start.x == self.end.x || self.start.y == self.end.y
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}
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pub fn expand(&self) -> impl Iterator<Item = Vector2D<usize>> {
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LinePoints::new(self)
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}
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}
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impl FromStr for Line {
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type Err = Infallible;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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let parts: Vec<_> = s.split(' ').collect();
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let start: Vec<_> = parts[0].split(',').map(|n| n.parse().unwrap()).collect();
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let end: Vec<_> = parts[2].split(',').map(|n| n.parse().unwrap()).collect();
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Ok(Line {
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start: Vector2D::new(start[0], start[1]),
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end: Vector2D::new(end[0], end[1]),
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})
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}
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}
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struct LinePoints {
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pos: Vector2D<isize>,
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step: Vector2D<isize>,
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points_left: usize,
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}
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impl LinePoints {
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fn new(line: &Line) -> Self {
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let start = line.start.as_isizes();
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let end = line.end.as_isizes();
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let delta = end - start;
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let step = Vector2D::new(delta.x.signum(), delta.y.signum());
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let len = usize::max(delta.x.unsigned_abs(), delta.y.unsigned_abs());
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Self {
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pos: start,
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step,
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points_left: len + 1,
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}
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}
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}
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impl Iterator for LinePoints {
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type Item = Vector2D<usize>;
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fn next(&mut self) -> Option<Self::Item> {
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if self.points_left == 0 {
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return None;
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}
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let current = self.pos;
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self.pos += self.step;
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self.points_left -= 1;
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Some(current.as_usizes())
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}
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}
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fn count_overlaps<'a>(it: impl IntoIterator<Item = &'a Line>) -> usize {
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let points: Vec<(usize, usize)> = it
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.into_iter()
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.flat_map(Line::expand)
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.map(Into::into)
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.collect();
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let (max_x, max_y) = points.iter().fold((0, 0), |(acc_x, acc_y), &(x, y)| {
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(usize::max(acc_x, x), usize::max(acc_y, y))
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});
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let mut field = vec![vec![0_usize; max_y + 1]; max_x + 1];
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let mut hits = 0;
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for (x, y) in points {
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let point = &mut field[x][y];
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if *point == 1 {
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hits += 1;
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}
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*point += 1;
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}
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hits
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}
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fn main() {
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let lines: Vec<Line> = stdin()
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.lock()
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.lines()
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.map(|s| s.unwrap().parse().unwrap())
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.collect();
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println!(
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"{}",
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count_overlaps(lines.iter().filter(|line| line.is_straight()))
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);
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println!("{}", count_overlaps(&lines));
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}
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