Day 3: Mull It Over

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FAQ

  • @[email protected]
    link
    fedilink
    11 day ago

    Rust

    Didn’t do anything crazy here – ended up using regex like a bunch of other folks.

    solution
    use regex::Regex;
    
    use crate::shared::util::read_lines;
    
    fn parse_mul(input: &[String]) -> (u32, u32) {
        // Lazy, but rejoin after having removed `\n`ewlines.
        let joined = input.concat();
        let re = Regex::new(r"mul\((\d+,\d+)\)|(do\(\))|(don't\(\))").expect("invalid regex");
    
        // part1
        let mut total1 = 0u32;
        // part2 -- adds `do()`s and `don't()`s
        let mut total2 = 0u32;
        let mut enabled = 1u32;
    
        re.captures_iter(&joined).for_each(|c| {
            let (_, [m]) = c.extract();
            match m {
                "do()" => enabled = 1,
                "don't()" => enabled = 0,
                _ => {
                    let product: u32 = m.split(",").map(|s| s.parse::<u32>().unwrap()).product();
                    total1 += product;
                    total2 += product * enabled;
                }
            }
        });
        (total1, total2)
    }
    
    pub fn solve() {
        let input = read_lines("inputs/day03.txt");
        let (part1_res, part2_res) = parse_mul(&input);
        println!("Part 1: {}", part1_res);
        println!("Part 2: {}", part2_res);
    }
    
    #[cfg(test)]
    mod test {
        use super::*;
    
        #[test]
        fn test_solution() {
            let test_input = vec![
                "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))".to_string(),
            ];
            let (p1, p2) = parse_mul(&test_input);
            eprintln!("P1: {p1}, P2: {p2}");
            assert_eq!(161, p1);
            assert_eq!(48, p2);
        }
    }
    
    

    Solution on my github (Made it public now)