10.rs

#![feature(test)]

type Input = Vec<String>;

fn setup(input: &str) -> Input {
    input.lines().map(|s| s.to_string()).collect()
}

fn part1(input: &Input) -> String {
    input
        .iter()
        .map(|line| {
            let mut stack = Vec::new();
            for c in line.chars() {
                if "([{<".contains(c) {
                    stack.push(c);
                } else {
                    let x = stack.pop().unwrap();
                    if !["()", "[]", "{}", "<>"].contains(&format!("{}{}", x, c).as_str()) {
                        return match c {
                            ')' => 3,
                            ']' => 57,
                            '}' => 1197,
                            '>' => 25137,
                            _ => panic!(),
                        };
                    }
                }
            }
            0
        })
        .sum::<u32>()
        .to_string()
}

fn part2(input: &Input) -> String {
    let mut scores: Vec<usize> = input
        .iter()
        .filter_map(|line| {
            let mut stack = Vec::new();
            for c in line.chars() {
                if "([{<".contains(c) {
                    stack.push(c);
                } else {
                    let x = stack.pop().unwrap();
                    if !["()", "[]", "{}", "<>"].contains(&format!("{}{}", x, c).as_str()) {
                        return None;
                    }
                }
            }
            let mut out = 0;
            for c in stack.iter().rev() {
                out = out * 5 + " ([{<".find(*c).unwrap();
            }
            Some(out)
        })
        .collect();
    scores.sort();
    scores[scores.len() / 2].to_string()
}

aoc::main!(2021, 10, ex: 1);