Day 2: Cube Conundrum


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  • CannotSleep420
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    1 year ago

    I’m a bit late to the party for day 2. Here’s my answer:

    use std::rc::Rc;
    
    use crate::utils::read_lines;
    
    #[derive(Clone, Copy, PartialEq, Eq)]
    enum Cube {
        Red(usize),
        Green(usize),
        Blue(usize),
    }
    
    #[derive(Clone, Copy, PartialEq, Eq)]
    struct Bag {
        pub red: usize,
        pub green: usize,
        pub blue: usize,
    }
    
    fn parse_num<'a, I>(mut group: I) -> usize
    where
        I: Iterator,
    {
        group
            .next()
            .expect("Should be number")
            .parse::()
            .expect("Should be number")
    }
    
    fn process_lines() -> impl Iterator> {
        read_lines("src/day_2/input.txt")
            .expect("Could not read file")
            .map(|line| {
                let line = line.expect("Should be line");
                (&line[(line.find(':').unwrap() + 1)..])
                    .split(';')
                    .flat_map(|section| section.split(","))
                    .map(|group| {
                        let mut group = group.trim().split(' ');
    
                        match group.next_back().expect("Should be color") {
                            "red" => Cube::Red(parse_num(group)),
                            "green" => Cube::Green(parse_num(group)),
                            "blue" => Cube::Blue(parse_num(group)),
                            c @ _ => panic!("Color {c} not recognized"),
                        }
                    })
                    .collect::>()
            })
            .into_iter()
    }
    
    pub fn solution_1() {
        let bag = Bag {
            red: 12,
            green: 13,
            blue: 14,
        };
        let sum: usize = process_lines()
            .enumerate()
            .map(|(i, line)| {
                let is_possible = line.iter().all(|cube| match cube {
                    Cube::Red(c) => *c <= bag.red,
                    Cube::Green(c) => *c <= bag.green,
                    Cube::Blue(c) => *c <= bag.blue,
                });
    
                if is_possible {
                    i + 1
                } else {
                    0
                }
            })
            .sum();
    
        println!("{sum}");
    }
    
    pub fn solution_2() {
        let powersum: usize = process_lines()
            .map(|line| {
                let bag = line.iter().fold(
                    Bag {
                        red: 0,
                        blue: 0,
                        green: 0,
                    },
                    |mut bag, cube| {
                        match *cube {
                            Cube::Red(n) => {
                                if n > bag.red {
                                    bag.red = n;
                                }
                            }
                            Cube::Green(n) => {
                                if n > bag.green {
                                    bag.green = n;
                                }
                            }
                            Cube::Blue(n) => {
                                if n > bag.blue {
                                    bag.blue = n;
                                }
                            }
                        }
    
                        bag
                    },
                );
    
                bag.red * bag.blue * bag.green
            })
            .sum();
    
        println!("{powersum}");
    }