AoC23/src/day01.rs

use regex::Regex;

pub fn run() {
    let input = include_str!("../input/day1.txt");
    // let input = r#"1abc2
    // pqr3stu8vwx
    // a1b2c3d4e5f
    // treb7uchet"#;
    // let input = r#"two1nine
    // eightwothree
    // abcone2threexyz
    // xtwone3four
    // 4nineeightseven2
    // zoneight234
    // 7pqrstsixteen"#;

    // let sum: u32 = input
    //     .lines()
    //     .filter(|s| !s.is_empty())
    //     .map(|s| find_digits(s))
    //     .sum();
    // dbg!(sum);

    dbg!(find_digits_part2("gdgj3f"));

    let sum2 = input
        .lines()
        .filter(|s| !s.is_empty())
        .map(|s| find_digits_part2(s))
        .sum::<u32>();
    dbg!(sum2);
}

fn find_digits(s: &str) -> u32 {
    let first = s
        .chars()
        .nth(s.find(|c: char| c.is_ascii_digit()).unwrap())
        .unwrap()
        .to_digit(10)
        .unwrap();
    let last = s
        .chars()
        .nth(s.rfind(|c: char| c.is_ascii_digit()).unwrap())
        .unwrap()
        .to_digit(10)
        .unwrap();
    first * 10 + last
}

fn find_digits_part2(s: &str) -> u32 {
    let re = Regex::new("^([1-9]|one|two|three|four|five|six|seven|eight|nine)").unwrap();
    let mut s = s.to_owned();
    let mut first: Option<u32> = None;
    let mut last: Option<u32> = None;
    while !s.is_empty() {
        if let Some(m) = re.find(&s) {
            last = Some(parse_digit(m.as_str()));
            if first == None {
                first = last;
            }
        }
        s.remove(0);
    }
    return first.unwrap() * 10 + last.unwrap();
}

fn parse_digit(s: &str) -> u32 {
    match s {
        "one" => 1,
        "two" => 2,
        "three" => 3,
        "four" => 4,
        "five" => 5,
        "six" => 6,
        "seven" => 7,
        "eight" => 8,
        "nine" => 9,
        _ => s.parse().unwrap(),
    }
}