AoC2021/src/day04.rs

use crate::Day;
use anyhow::Result;

#[derive(Clone)]
pub struct Day04 {
    numbers: Vec<u32>,
    boards: Vec<Board>,
}

#[derive(Clone, Eq, PartialEq, Debug)]
struct Board(Vec<Vec<Option<u32>>>);

impl Day for Day04 {
    fn init(content: String) -> Result<Self> {
        let l = content.lines().collect::<Vec<&str>>();
        let (a, b) = l.split_at(2);
        let first = a[0];
        let nums = first.split(',').map(str::parse).collect::<Result<Vec<_>, _>>()?;

        let split = b.split(|x| x.is_empty());

        let boards = split.map(|vecs|
            vecs.iter().map(
                |vec| vec.split_ascii_whitespace().map(
                    |x| x.parse::<u32>().expect("foo")
                ).map(Option::Some).collect()).collect()
        ).map(Board).collect();

        Ok(Self {
            numbers: nums,
            boards,
        })
    }

    fn part1(&self) -> Result<String> {
        let z = self.clone();
        let mut boards = z.boards;
        for number in z.numbers {
            for board in &mut boards {
                let res = board.mark(number);
                if res {
                    let s = board.unmarked_sum();
                    return Ok(format!("{}", s * number));
                }
            }
        }

        Err(anyhow::Error::msg("could not find a working sum..."))
    }

    fn part2(&self) -> Result<String> {
        let z = self.clone();
        let mut boards = z.boards;
        for number in z.numbers {
            let len = boards.len();
            for board in &mut boards {
                let res = board.mark(number);
                if res && len == 1 {
                    let s = board.unmarked_sum();
                    return Ok(format!("{}", s * number));
                }
            }
            boards = boards.iter().filter(|x| !x.complete()).cloned().collect();
        }

        Err(anyhow::Error::msg("could not find a working sum..."))
    }
}

impl Board {
    fn mark(&mut self, num: u32) -> bool {
        #[allow(clippy::manual_flatten)]
        for columns in &mut self.0 {
            for row in columns.iter_mut() {
                if let Some(v) = row {
                    if *v == num {
                        *row = None;
                    }
                }
            }
        }
        self.check_rows() || self.check_columns()
    }

    fn complete(&self) -> bool {
        self.check_rows() || self.check_columns()
    }

    fn check_rows(&self) -> bool {
        for columns in &self.0 {
            if columns.iter().all(Option::is_none) {
                return true;
            }
        }
        false
    }
    fn check_columns(&self) -> bool {
        let t = Board::transpose(&self.0);
        for rows in t {
            if rows.iter().all(Option::is_none) {
                return true;
            }
        }
        false
    }

    fn transpose<T: Clone>(v: &[Vec<T>]) -> Vec<Vec<T>> {
        assert!(!v.is_empty());
        let len = v[0].len();
        let mut iters: Vec<_> = v.iter().map(|n| n.iter()).collect();
        (0..len)
            .map(|_| {
                iters
                    .iter_mut()
                    .map(|n| n.next().unwrap())
                    .cloned()
                    .collect::<Vec<T>>()
            })
            .collect()
    }

    fn unmarked_sum(&self) -> u32 {
        self.0.iter().map(|x| x.iter().flatten().sum::<u32>()).sum()
    }
}

#[cfg(test)]
mod tests {
    use crate::{Day04, day_tests};
    use crate::day04::Board;
    use crate::day::Day;
    use anyhow::Result;

    const INPUT: &str = r"7,4,9,5,11,17,23,2,0,14,21,24,10,16,13,6,15,25,12,22,18,20,8,19,3,26,1

22 13 17 11  0
 8  2 23  4 24
21  9 14 16  7
 6 10  3 18  5
 1 12 20 15 19

 3 15  0  2 22
 9 18 13 17  5
19  8  7 25 23
20 11 10 24  4
14 21 16 12  6

14 21 17 24  4
10 16 15  9 19
18  8 23 26 20
22 11 13  6  5
 2  0 12  3  7";

    #[test]
    fn board_mark_test() {
        let mut b = Board(vec![vec![Some(10)]]);
        let res = b.mark(10);
        assert_eq!(b.0[0][0], None);
        assert!(res)
    }

    #[test]
    fn board_rows_are_marked() {
        let b = Board(vec![vec![None, None, None, None], vec![Some(10), Some(10), Some(10), Some(10)]]);
        assert!(b.check_rows())
    }

    #[test]
    fn board_rows_are_not_marked() {
        let b = Board(vec![vec![None, None, Some(10), None]]);
        assert!(!b.check_rows())
    }

    #[test]
    fn board_cols_are_marked() {
        let b = Board(vec![vec![None], vec![None], vec![None], vec![None]]);
        assert!(b.check_columns())
    }

    #[test]
    fn board_cols_are_not_marked() {
        let b = Board(vec![vec![None], vec![None], vec![Some(10)], vec![None]]);
        assert!(!b.check_columns())
    }

    #[test]
    fn board_cols_are_not_rows() {
        let b = Board(vec![vec![None, Some(10)], vec![None, Some(10)], vec![None, Some(10)], vec![None, Some(10)]]);
        assert!(!b.check_rows())
    }

    #[test]
    fn part1_test() -> Result<()> {
        let t = Day04::init(INPUT.to_string())?;
        let p1 = t.part1()?;
        assert_eq!("4512", p1);
        Ok(())
    }

    #[test]
    fn part2_test() -> Result<()> {
        let t = Day04::init(INPUT.to_string())?;
        let p2 = t.part2()?;
        assert_eq!("1924", p2);
        Ok(())
    }

    day_tests!(Day04, "04", "8136", "12738");
}