AOC 2022, Day 1

Day1.rs

fn main() {
    let input = include_str!("input.txt");
    let elves = get_elves(input);
    let answer_1 = part_1(&elves);
    let answer_2 = part_2(&elves);
    println!("{}", answer_1);
    println!("{}", answer_2);
}


fn get_elves(input: &str) -> Vec<Vec<u32>> {
    input.lines()
        .fold((Vec::new(), Vec::new()), |(mut elves, mut elf), line| {
            if line.is_empty() {
                elves.push(elf);
                (elves, Vec::new())
            } else {
                elf.push(line.parse().unwrap());
                (elves, elf)
            }
        }).0
}

/// Returns the total calories of the elf with the most calories
/// # Examples
/// ```
/// let elves = vec![vec![1000, 2000, 3000], vec![4000], vec![5000, 6000], vec![7000, 8000, 9000], vec![10000]];
/// assert_eq!(part_1(&elves), 24000);
/// ```

fn part_1(elves: &Vec<Vec<u32>>) -> u32 {
    elves
        .iter()
        .map(|elf| elf.iter().sum())
        .max()
        .unwrap()
}


/// Returns the sum of the top three elves
/// # Examples
/// ```
/// let elves = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9], vec![10, 11, 12]];
/// assert_eq!(part_2(&elves), 72);
/// ```
///
/// You can also, if you add itertools to your Cargo.toml, use the itertools crate to do this in one line
/// ```
/// use itertools::Itertools;
/// let elves = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9], vec![10, 11, 12]];
/// assert_eq!(elves.iter().map(|elf| elf.iter().sum()).sorted().rev().take(3).sum::<u32>(), 72);
/// ```
fn part_2(elves: &Vec<Vec<u32>>) -> u32 {
    elves.iter()
        .map(|elf| elf.iter().sum::<u32>())
        .fold(vec![0, 0, 0], |mut acc, x| {
            if x > acc[0] {
                acc[2] = acc[1];
                acc[1] = acc[0];
                acc[0] = x;
            } else if x > acc[1] {
                acc[2] = acc[1];
                acc[1] = x;
            } else if x > acc[2] {
                acc[2] = x;
            }
            acc
        })
        .iter()
        .sum()
}


#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_part_1() {
        let elves = vec![vec![1000, 2000, 3000], vec![4000], vec![5000, 6000], vec![7000, 8000, 9000], vec![10000]];
        assert_eq!(part_1(&elves), 24000);
    }

    #[test]
    fn test_part_2() {
        let elves = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9], vec![10, 11, 12]];
        assert_eq!(part_2(&elves), 72);
    }

    #[test]
    fn test_part_2_with_itertools() {
        use itertools::Itertools;
        let elves = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9], vec![10, 11, 12]];
        assert_eq!(elves.iter().map(|elf| elf.iter().sum::<u32>()).sorted().rev().take(3).sum::<u32>(), 72);
    }
}