Last active
December 5, 2023 20:02
-
-
Save anden3/a4582a3fffae8042593ffcbf11c83076 to your computer and use it in GitHub Desktop.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| use std::ops::Range; | |
| use rangemap::RangeSet; | |
| trait RangeExt { | |
| fn add(&self, offset: i64) -> Self; | |
| } | |
| impl RangeExt for Range<i64> { | |
| fn add(&self, offset: i64) -> Self { | |
| (self.start + offset)..(self.end + offset) | |
| } | |
| } | |
| pub fn part2(input: &str) -> i64 { | |
| let mut seeds = RangeSet::<i64>::new(); | |
| for section in input.split("\n\n") { | |
| let (label, values) = section.split_once(':').unwrap(); | |
| if label == "seeds" { | |
| let seed_vec = values | |
| .trim() | |
| .split_ascii_whitespace() | |
| .map(|v| v.parse::<i64>().unwrap()) | |
| .collect::<Vec<_>>(); | |
| for pair in seed_vec.chunks_exact(2) { | |
| let (start, length) = (pair[0], pair[1]); | |
| seeds.insert(start..(start + length)); | |
| } | |
| continue; | |
| } | |
| let mut next_seeds = RangeSet::<i64>::new(); | |
| for line in values.trim().lines() { | |
| let mut line_values = line.split_ascii_whitespace().map(|v| v.parse().unwrap()); | |
| let [dest, source, length]: [i64; 3] = | |
| std::array::from_fn(|_| line_values.next().unwrap()); | |
| let diff = dest - source; | |
| let source_range = source..(source + length); | |
| let mut to_remove = Vec::new(); | |
| for overlapping in seeds.overlapping(&source_range) { | |
| let range = match ( | |
| source_range.contains(&overlapping.start), | |
| source_range.contains(&overlapping.end), | |
| ) { | |
| (true, true) => { | |
| overlapping.clone() | |
| } | |
| (true, false) => { | |
| overlapping.start..source_range.end | |
| } | |
| (false, true) => { | |
| source_range.start..overlapping.end | |
| } | |
| (false, false) => { | |
| source_range.clone() | |
| } | |
| }; | |
| next_seeds.insert(range.add(diff)); | |
| to_remove.push(range); | |
| } | |
| for range in to_remove { | |
| seeds.remove(range); | |
| } | |
| } | |
| next_seeds.extend(seeds); | |
| seeds = next_seeds; | |
| } | |
| seeds.into_iter().next().unwrap().start | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment