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use advent_of_code::prelude::*;
#[derive(Debug)]
struct Board {
numbers: Vec<u8>,
marked: Vec<bool>,
}
impl Board {
fn new(numbers: Vec<u8>) -> Self {
let len = numbers.len();
Self {
numbers,
marked: vec![false; len],
}
}
fn won(&self) -> bool {
let wins = [
[0, 1, 2, 3, 4],
[5, 6, 7, 8, 9],
[10, 11, 12, 13, 14],
[15, 16, 17, 18, 19],
[20, 21, 22, 23, 24],
[0, 5, 10, 15, 20],
[1, 6, 11, 16, 21],
[2, 7, 12, 17, 22],
[3, 8, 13, 18, 23],
[4, 9, 14, 19, 24],
];
wins.iter().any(|win| win.iter().all(|i| self.marked[*i]))
}
fn mark(&mut self, called: u8) {
for (i, n) in self.numbers.iter().enumerate() {
if called == *n {
self.marked[i] = true;
}
}
}
fn value(&self) -> u64 {
self.marked
.iter()
.zip(self.numbers.iter())
.filter_map(
|(marked, n)| {
if !*marked {
Some(u64::from(*n))
} else {
None
}
},
)
.sum()
}
}
#[derive(Debug)]
pub struct Game {
inputs: Vec<u8>,
boards: Vec<Board>,
}
impl Game {
fn parse<T: std::io::Read>(input: T) -> Result<Self> {
let mut lines = parse::raw_lines(input).peekable();
let line = lines.next().ok_or_else(|| anyhow!("missing line"))?;
let inputs = line
.trim()
.split(',')
.map(|s| s.parse())
.collect::<Result<Vec<u8>, _>>()?;
lines.next();
let mut boards = vec![];
while lines.peek().is_some() {
let mut numbers = vec![];
for line in parse::chunk(&mut lines) {
numbers.extend(
line.split_whitespace()
.map(|s| s.parse())
.collect::<Result<Vec<u8>, _>>()?,
);
}
boards.push(Board::new(numbers));
}
Ok(Self { inputs, boards })
}
fn find_first_winner(self) -> Option<(u8, Board)> {
let Self { inputs, mut boards } = self;
let mut won = None;
for n in inputs {
for (i, board) in boards.iter_mut().enumerate() {
board.mark(n);
if board.won() {
won = Some((n, i));
break;
}
}
if won.is_some() {
break;
}
}
won.map(|(n, i)| (n, boards.swap_remove(i)))
}
fn find_last_winner(self) -> Option<(u8, Board)> {
let Self { inputs, mut boards } = self;
let mut last_won = None;
for n in inputs {
let mut won = vec![];
for (i, board) in boards.iter_mut().enumerate() {
board.mark(n);
if board.won() {
won.push(i);
}
}
if boards.len() == won.len() {
last_won = Some((n, won[0]));
break;
}
for i in won.into_iter().rev() {
boards.swap_remove(i);
}
if boards.is_empty() {
break;
}
}
last_won.map(|(n, i)| (n, boards.swap_remove(i)))
}
}
pub fn parse(fh: File) -> Result<Game> {
Game::parse(fh)
}
pub fn part1(game: Game) -> Result<u64> {
if let Some((n, board)) = game.find_first_winner() {
Ok(u64::from(n) * board.value())
} else {
bail!("couldn't find winner")
}
}
pub fn part2(game: Game) -> Result<u64> {
if let Some((n, board)) = game.find_last_winner() {
Ok(u64::from(n) * board.value())
} else {
bail!("couldn't find winner")
}
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2021, 4).unwrap()).unwrap()).unwrap(),
2745
);
assert_eq!(
part2(parse(parse::data(2021, 4).unwrap()).unwrap()).unwrap(),
6594
);
}
|
