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|
use advent_lib::prelude::*;
fn main() -> Result<()> {
let mut args = std::env::args();
if args.len() != 2 {
eprintln!("Usage: advent input");
}
let _ = args.next();
let filename = args.next().unwrap();
let input = advent_lib::read_lines_file(&filename)?;
let mut total_score = 0;
let mut incomplete_lines = Vec::new();
for line in &input {
let mut chars = line.chars().peekable();
let score = parse(&mut chars);
total_score += score;
if score == 0 {
incomplete_lines.push(line.clone());
}
}
println!("{}", total_score);
let mut completion_scores = Vec::new();
for line in &incomplete_lines {
let mut chars = line.chars().peekable();
let completion = repair(&mut chars, true).unwrap();
let mut score: i64 = 0;
for c in completion.chars() {
score *= 5;
score += match c {
')' => 1,
']' => 2,
'}' => 3,
'>' => 4,
_ => 0,
}
}
completion_scores.push(score);
}
completion_scores.sort();
let second_score = completion_scores[completion_scores.len() / 2];
println!("{}", second_score);
Ok(())
}
fn parse(chars: &mut std::iter::Peekable<std::str::Chars<'_>>) -> i64 {
match chars.next() {
None => {
return 0;
}
Some(open) => {
let open = open.clone();
loop {
match chars.peek() {
None => {
return 0;
}
Some(c) => {
let c = *c;
if "([{<".contains(|d| c == d) {
let score = parse(chars);
if score != 0 {
return score;
}
} else {
let _ = chars.next();
match (open, c) {
('(', ')') => { return 0; }
('[', ']') => { return 0; }
('{', '}') => { return 0; }
('<', '>') => { return 0; }
(_, ')') => { return 3; }
(_, ']') => { return 57; }
(_, '}') => { return 1197; }
(_, '>') => { return 25137; }
_ => { }
}
}
}
}
}
}
}
}
fn repair(chars: &mut std::iter::Peekable<std::str::Chars<'_>>,
is_top_level: bool)
-> Option<String>
{
loop {
match chars.next() {
None => {
return Some(String::new());
}
Some(open) => {
let open = open.clone();
loop {
match chars.peek() {
None => {
let mut result = String::new();
result.push(match open {
'(' => ')',
'[' => ']',
'{' => '}',
'<' => '>',
_ => panic!("alas"),
});
return Some(result);
}
Some(c) => {
let c = *c;
if "([{<".contains(|d| c == d) {
match repair(chars, false) {
None => { }
Some(mut result) => {
result.push(match open {
'(' => ')',
'[' => ']',
'{' => '}',
'<' => '>',
_ => panic!("alas"),
});
return Some(result);
}
}
} else {
let _ = chars.next();
if is_top_level {
break;
} else {
return None;
}
}
}
}
}
}
}
}
}
|