From 3ae4f2fe5dc1ba14e0bf81df14a0f2373cdd3182 Mon Sep 17 00:00:00 2001 From: June McEnroe Date: Fri, 15 Dec 2017 22:24:19 -0500 Subject: Day 12 --- 2017/src/bin/day12.rs | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 2017/src/bin/day12.rs (limited to '2017/src/bin') diff --git a/2017/src/bin/day12.rs b/2017/src/bin/day12.rs new file mode 100644 index 0000000..b133ba6 --- /dev/null +++ b/2017/src/bin/day12.rs @@ -0,0 +1,53 @@ +use std::collections::{HashMap, HashSet}; +use std::io::{self, Read}; + +fn solve1(input: &str) -> usize { + let mut pipes: HashMap> = HashMap::new(); + for line in input.lines() { + let mut words = line.split_whitespace(); + let src = words.next().unwrap().parse().unwrap(); + assert_eq!(Some("<->"), words.next()); + for dest in words { + let dest = dest.trim_right_matches(',').parse().unwrap(); + pipes.entry(src).or_insert(vec![]).push(dest); + pipes.entry(dest).or_insert(vec![]).push(src); + } + } + + let mut group = HashSet::new(); + group.insert(0); + + let mut prev = None; + while Some(group.len()) != prev { + prev = Some(group.len()); + for (src, dests) in &pipes { + if group.contains(src) { + group.extend(dests); + } + } + } + + group.len() +} + +fn main() { + let mut input = String::new(); + io::stdin().read_to_string(&mut input).unwrap(); + + println!("Part 1: {}", solve1(&input)); +} + +#[test] +fn part1() { + assert_eq!(6, solve1( +"\ +0 <-> 2 +1 <-> 1 +2 <-> 0, 3, 4 +3 <-> 2, 4 +4 <-> 2, 3, 6 +5 <-> 6 +6 <-> 4, 5 +" + )); +} -- cgit 1.4.1