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//! Awful...
use std::{cmp::Ordering, collections::{HashMap, HashSet}, error::Error, fs::File, io::{BufRead, BufReader}};
fn main() -> Result<(), Box<dyn Error>> {
let f = File::open("input/5.test")?;
let mut f = BufReader::new(f);
let mut must_precede: HashMap<i64, HashSet<i64>> = HashMap::new();
let mut line = String::new();
loop {
line.clear();
f.read_line(&mut line)?;
let line = line.trim_end();
if line.is_empty() { break };
let (lhs, rhs) = line.split_once('|').ok_or("Invalid dependency line")?;
must_precede.entry(lhs.parse()?).or_default().insert(rhs.parse()?);
}
let mut pages: Vec<i64> = Vec::new();
let mut p1_total = 0;
let mut p2_total = 0;
loop {
line.clear();
if f.read_line(&mut line)? == 0 {
break;
};
pages.clear();
// Ugh...
pages.extend(line.trim_end().split(',').map(|p| p.parse::<i64>().unwrap()));
let mut valid = true;
'outer: for (i, page) in pages.iter().enumerate().skip(1) {
let Some(succ) = must_precede.get(page) else {
continue;
};
for p in &pages[0..i] {
if succ.contains(p) {
valid = false;
break 'outer;
}
}
}
if valid {
p1_total += pages[pages.len() / 2];
} else {
pages.sort_by(|a, b| {
if let Some(succ) = must_precede.get(a) {
if succ.contains(b) {
Ordering::Less
} else {
Ordering::Greater
}
} else {
Ordering::Equal
}
});
p2_total += pages[pages.len() / 2];
}
}
println!("{p1_total}\n{p2_total}");
Ok(())
}
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