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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,225 @@ | ||
| use std::cmp::{max, min, Ordering}; | ||
| use std::collections::HashMap; | ||
|
|
||
| type Comparison = (char, Ordering, u32); | ||
| type Rule<'a> = Vec<(&'a str, Option<Comparison>)>; | ||
|
|
||
| #[derive(Clone, Debug)] | ||
| struct Point<T> { | ||
| x: T, | ||
| m: T, | ||
| a: T, | ||
| s: T, | ||
| } | ||
|
|
||
| impl<T> Point<T> { | ||
| fn get(&self, key: char) -> Option<&T> { | ||
| match key { | ||
| 'x' => Some(&self.x), | ||
| 'm' => Some(&self.m), | ||
| 'a' => Some(&self.a), | ||
| 's' => Some(&self.s), | ||
| _ => None, | ||
| } | ||
| } | ||
|
|
||
| fn get_mut(&mut self, key: char) -> Option<&mut T> { | ||
| match key { | ||
| 'x' => Some(&mut self.x), | ||
| 'm' => Some(&mut self.m), | ||
| 'a' => Some(&mut self.a), | ||
| 's' => Some(&mut self.s), | ||
| _ => None, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn parse_rule(line: &str) -> Option<(&str, Rule)> { | ||
| let (name, rest) = line.split_once('{')?; | ||
| let rest = rest.strip_suffix('}')?; | ||
| Some(( | ||
| name, | ||
| rest.split(',') | ||
| .map(|s| { | ||
| let Some((comparison, name)) = s.split_once(':') else { | ||
| return Some((s, None)); | ||
| }; | ||
| let mut chars = comparison.chars(); | ||
| let key = chars.next()?; | ||
| let ordering = match chars.next()? { | ||
| '<' => Ordering::Less, | ||
| '>' => Ordering::Greater, | ||
| _ => return None, | ||
| }; | ||
| Some(( | ||
| name, | ||
| Some((key, ordering, chars.as_str().parse::<u32>().ok()?)), | ||
| )) | ||
| }) | ||
| .collect::<Option<Vec<_>>>()?, | ||
| )) | ||
| } | ||
|
|
||
| fn parse_point(line: &str) -> Option<Point<u32>> { | ||
| let line = line.strip_prefix('{')?.strip_suffix('}')?; | ||
| let (mut x, mut m, mut a, mut s) = (None, None, None, None); | ||
| for part in line.split(',') { | ||
| let (option, part) = if let Some(part) = part.strip_prefix("x=") { | ||
| (&mut x, part) | ||
| } else if let Some(part) = part.strip_prefix("m=") { | ||
| (&mut m, part) | ||
| } else if let Some(part) = part.strip_prefix("a=") { | ||
| (&mut a, part) | ||
| } else if let Some(part) = part.strip_prefix("s=") { | ||
| (&mut s, part) | ||
| } else { | ||
| return None; | ||
| }; | ||
| if option.replace(part.parse().ok()?).is_some() { | ||
| return None; | ||
| } | ||
| } | ||
| Some(Point { | ||
| x: x?, | ||
| m: m?, | ||
| a: a?, | ||
| s: s?, | ||
| }) | ||
| } | ||
|
|
||
| pub fn part1(data: &str) -> u32 { | ||
| let mut lines = data.lines().skip_while(|line| line.is_empty()); | ||
| let rules = lines | ||
| .by_ref() | ||
| .map_while(parse_rule) | ||
| .collect::<HashMap<_, _>>(); | ||
| lines | ||
| .filter_map(|line| { | ||
| let point = parse_point(line)?; | ||
| let mut name = "in"; | ||
| while let Some(rules) = rules.get(name) { | ||
| name = rules | ||
| .iter() | ||
| .find(|(_, comparison)| { | ||
| comparison.map_or(true, |(key, ordering, expected)| { | ||
| point | ||
| .get(key) | ||
| .map_or(false, |actual| actual.cmp(&expected) == ordering) | ||
| }) | ||
| })? | ||
| .0; | ||
| } | ||
| if name == "A" { | ||
| Some(point.x + point.m + point.a + point.s) | ||
| } else { | ||
| None | ||
| } | ||
| }) | ||
| .sum() | ||
| } | ||
|
|
||
| fn part2_helper(rules: &HashMap<&str, Rule>, name: &str, bounds: Point<(u32, u32)>) -> u64 { | ||
| let Point { | ||
| x: (x0, x1), | ||
| m: (m0, m1), | ||
| a: (a0, a1), | ||
| s: (s0, s1), | ||
| } = bounds; | ||
| if x0 > x1 || m0 > m1 || a0 > a1 || s0 > s1 { | ||
| return 0; | ||
| } | ||
| if name == "A" { | ||
| return (x1 - x0 + 1) as u64 | ||
| * (m1 - m0 + 1) as u64 | ||
| * (a1 - a0 + 1) as u64 | ||
| * (s1 - s0 + 1) as u64; | ||
| } | ||
| let Some(rule) = rules.get(name) else { | ||
| return 0; | ||
| }; | ||
| rule.iter() | ||
| .scan( | ||
| Some(bounds.clone()), | ||
| |st, &(name, comparison)| -> Option<u64> { | ||
| let Some((key, ordering, value)) = comparison else { | ||
| return Some(part2_helper(rules, name, st.take()?)); | ||
| }; | ||
| let mut bounds = st.clone()?; | ||
| let Some(((lo0, hi0), (lo1, hi1))) = | ||
| bounds.get_mut(key).zip(st.as_mut()?.get_mut(key)) | ||
| else { | ||
| return Some(0); | ||
| }; | ||
| match ordering { | ||
| Ordering::Less => { | ||
| *hi0 = min(*hi0, value - 1); | ||
| *lo1 = max(*lo1, value); | ||
| } | ||
| Ordering::Greater => { | ||
| *lo0 = max(*lo0, value + 1); | ||
| *hi1 = min(*hi1, value); | ||
| } | ||
| Ordering::Equal => panic!(), | ||
| } | ||
| if lo1 > hi1 { | ||
| *st = None; | ||
| } | ||
| Some(part2_helper(rules, name, bounds)) | ||
| }, | ||
| ) | ||
| .sum() | ||
| } | ||
|
|
||
| pub fn part2(data: &str) -> u64 { | ||
| part2_helper( | ||
| &data | ||
| .lines() | ||
| .skip_while(|line| line.is_empty()) | ||
| .map_while(parse_rule) | ||
| .collect::<HashMap<_, _>>(), | ||
| "in", | ||
| Point { | ||
| x: (1, 4000), | ||
| m: (1, 4000), | ||
| a: (1, 4000), | ||
| s: (1, 4000), | ||
| }, | ||
| ) | ||
| } | ||
|
|
||
| #[cfg(test)] | ||
| mod tests { | ||
| use super::*; | ||
| use indoc::indoc; | ||
| use pretty_assertions::assert_eq; | ||
|
|
||
| static EXAMPLE: &str = indoc! {" | ||
| px{a<2006:qkq,m>2090:A,rfg} | ||
| pv{a>1716:R,A} | ||
| lnx{m>1548:A,A} | ||
| rfg{s<537:gd,x>2440:R,A} | ||
| qs{s>3448:A,lnx} | ||
| qkq{x<1416:A,crn} | ||
| crn{x>2662:A,R} | ||
| in{s<1351:px,qqz} | ||
| qqz{s>2770:qs,m<1801:hdj,R} | ||
| gd{a>3333:R,R} | ||
| hdj{m>838:A,pv} | ||
| {x=787,m=2655,a=1222,s=2876} | ||
| {x=1679,m=44,a=2067,s=496} | ||
| {x=2036,m=264,a=79,s=2244} | ||
| {x=2461,m=1339,a=466,s=291} | ||
| {x=2127,m=1623,a=2188,s=1013} | ||
| "}; | ||
|
|
||
| #[test] | ||
| fn part1_examples() { | ||
| assert_eq!(19114, part1(EXAMPLE)); | ||
| } | ||
|
|
||
| #[test] | ||
| fn part2_examples() { | ||
| assert_eq!(167409079868000, part2(EXAMPLE)); | ||
| } | ||
| } |
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