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use crate::prelude::*;
fn fire(
mut xv: i64,
mut yv: i64,
xrange: &std::ops::RangeInclusive<i64>,
yrange: &std::ops::RangeInclusive<i64>,
) -> Option<i64> {
let mut xpos = 0;
let mut ypos = 0;
let mut max_height = 0;
loop {
if xrange.contains(&xpos) && yrange.contains(&ypos) {
return Some(max_height);
} else if (xv >= 0 && xpos > *xrange.end())
|| (xv <= 0 && xpos < *xrange.start())
|| (ypos < *yrange.start())
{
return None;
}
xpos += xv;
ypos += yv;
if ypos > max_height {
max_height = ypos;
}
match xv.cmp(&0) {
Ordering::Greater => {
xv -= 1;
}
Ordering::Less => {
xv += 1;
}
_ => {}
}
yv -= 1;
}
}
pub fn parse(
fh: File,
) -> Result<(std::ops::RangeInclusive<i64>, std::ops::RangeInclusive<i64>)> {
let rx =
Regex::new(r"target area: x=(-?\d+)..(-?\d+), y=(-?\d+)..(-?\d+)")
.unwrap();
let line = parse::lines(fh).next().unwrap();
let captures = rx.captures(&line).unwrap();
let xrange: std::ops::RangeInclusive<i64> =
captures[1].parse().unwrap()..=captures[2].parse().unwrap();
let yrange: std::ops::RangeInclusive<i64> =
captures[3].parse().unwrap()..=captures[4].parse().unwrap();
Ok((xrange, yrange))
}
pub fn part1(
(xrange, yrange): (
std::ops::RangeInclusive<i64>,
std::ops::RangeInclusive<i64>,
),
) -> Result<i64> {
let mut max_height = 0;
for xv in *xrange.start().min(&0)..=*xrange.end().max(&0) {
for yv in *yrange.start().min(&0)
..=yrange.start().abs().max(yrange.end().abs())
{
if let Some(height) = fire(xv, yv, &xrange, &yrange) {
if height > max_height {
max_height = height;
}
}
}
}
Ok(max_height)
}
pub fn part2(
(xrange, yrange): (
std::ops::RangeInclusive<i64>,
std::ops::RangeInclusive<i64>,
),
) -> Result<i64> {
let mut count = 0;
for xv in *xrange.start().min(&0)..=*xrange.end().max(&0) {
for yv in *yrange.start().min(&0)
..=yrange.start().abs().max(yrange.end().abs())
{
if fire(xv, yv, &xrange, &yrange).is_some() {
count += 1;
}
}
}
Ok(count)
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2021, 17).unwrap()).unwrap()).unwrap(),
5886
);
assert_eq!(
part2(parse(parse::data(2021, 17).unwrap()).unwrap()).unwrap(),
1806
);
}
|
