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|
use nom::{
bytes::complete::tag,
character::complete::{char as nom_char, line_ending, u32 as nom_u32},
combinator::map,
multi::separated_list1,
sequence::tuple,
IResult,
};
use std::{collections::BTreeMap, fs};
fn main() -> Result<(), Box<dyn std::error::Error>> {
let input = fs::read_to_string("inputs/day_5.txt")?;
let lines = parse_lines(&input).unwrap().1;
{
let mut map_simple = Bitmap::default();
for line in &lines {
map_simple.mark_line_only_simple(line);
}
dbg!(map_simple.count_overlapped_points());
}
{
let mut map = Bitmap::default();
for line in &lines {
map.mark_line(line);
}
dbg!(map.count_overlapped_points());
}
Ok(())
}
#[derive(Default)]
struct Bitmap(BTreeMap<Point, usize>);
impl Bitmap {
fn mark_line_only_simple(&mut self, l: &Line) {
if l.is_horizontal() {
for x in l.a.x..=l.b.x {
self.mark_point(&Point { x, y: l.a.y });
}
} else if l.is_vertical() {
for y in l.a.y..=l.b.y {
self.mark_point(&Point { x: l.a.x, y });
}
} else {
}
}
fn mark_line(&mut self, l: &Line) {
if l.is_horizontal() {
for x in l.a.x..=l.b.x {
self.mark_point(&Point { x, y: l.a.y });
}
} else if l.is_vertical() {
for y in l.a.y..=l.b.y {
self.mark_point(&Point { x: l.a.x, y });
}
} else if l.is_diagonal_up() {
for delta in 0..=(l.b.x - l.a.x) {
self.mark_point(&Point {
x: l.a.x + delta,
y: l.a.y + delta,
});
}
} else if l.is_diagonal_down() {
for delta in 0..=(l.b.x - l.a.x) {
let reverse_delta = l.b.x - l.a.x - delta;
self.mark_point(&Point {
x: l.a.x + delta,
y: l.b.y + reverse_delta,
});
}
} else {
panic!("There shouldn't be other cases...")
}
}
fn mark_point(&mut self, p: &Point) {
*self.0.entry(p.clone()).or_insert(0) += 1;
}
fn count_overlapped_points(&self) -> usize {
self.0.values().filter(|v| **v > 1).count()
}
}
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
struct Point {
x: u32,
y: u32,
}
#[derive(Debug)]
struct Line {
a: Point,
b: Point,
}
impl Line {
fn is_horizontal(&self) -> bool {
self.a.y == self.b.y
}
fn is_vertical(&self) -> bool {
self.a.x == self.b.x
}
fn is_diagonal_up(&self) -> bool {
self.a.x < self.b.x && self.a.y < self.b.y
}
fn is_diagonal_down(&self) -> bool {
self.a.x < self.b.x && self.a.y > self.b.y
}
}
fn parse_lines(input: &str) -> IResult<&str, Vec<Line>> {
separated_list1(line_ending, parse_line)(input)
}
fn parse_line(input: &str) -> IResult<&str, Line> {
map(
tuple((parse_point, tag(" -> "), parse_point)),
|(a, _, b)| {
if a < b {
Line { a, b }
} else {
Line { a: b, b: a }
}
},
)(input)
}
fn parse_point(input: &str) -> IResult<&str, Point> {
map(tuple((nom_u32, nom_char(','), nom_u32)), |(x, _, y)| {
Point { x, y }
})(input)
}
|
