day03.rs

use std::collections::HashSet;

use aoc_core::prelude::*;
use regex::Regex;

fn part1(input: &Input) -> isize {
    let re = Regex::new(r"mul\((\d+),(\d+)\)").unwrap();

    re
        .captures_iter(&input.raw)
        .map(|x| x.extract())
        .map(|(_, [x, y])| x.parse::<isize>().unwrap() * y.parse::<isize>().unwrap())
        .sum()
}

fn part2(input: &Input) -> isize {
    let re = Regex::new(r"mul\((\d+),(\d+)\)|(don't|do)").unwrap();

    re
        .captures_iter(&input.raw)
        .fold((true, 0), |(mut flag, mut result), cap| {
            if let Some(word) = cap.get(3) {
                flag = match &cap[3] {
                    "do" => true,
                    "don't" => false,
                    _ => false
                };
            }

            if flag {
                if let (Some(a), Some(b)) = (cap.get(1), cap.get(2)) {
                    let a: isize = a.as_str().parse().unwrap();
                    let b: isize = b.as_str().parse().unwrap();

                    result += a.checked_mul(b).unwrap();
                }
            }

            (flag, result)
        })
        .1
}

runner!();

#[cfg(test)]
#[test]
fn test() {
    let input = Input::new("xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))".to_string());
    assert_eq!(part1(&input), 161, "Part 1");

    let input = Input::new("xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))".to_string());
    assert_eq!(part2(&input), 48, "Part 2");
}