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advent-of-code-2021
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Handle multiple winners in a day 4 turn a bit more gracefully

master
Nick Krichevsky 2021-12-04 14:00:00 -05:00
parent 846b02a815
commit ce9fb3e431
1 changed files with 28 additions and 10 deletions
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38
day4/src/main.rs
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@ -149,11 +149,13 @@ impl BingoBoard {
}
impl<'a> Iterator for BingoPlayer<'a> {
type Item = (u8, BingoBoard);
// Yields the winning call and all of the boards that won with that call
type Item = (u8, Vec<BingoBoard>);
fn next(&mut self) -> Option<Self::Item> {
while let Some(call) = self.game.calls.pop_front() {
let boards = &mut self.game.boards;
let mut winning_board: Option<BingoBoard> = None;
let mut winning_boards: Vec<BingoBoard> = vec![];
for BoardState {
won: board_has_won,
board,
@ -167,13 +169,11 @@ impl<'a> Iterator for BingoPlayer<'a> {
board.mark_n(call);
if board.is_winner() {
// This is a bit of a hack, but it will work given the use of the iterator in part 2.
// (in production code I'd probably return _all_ boards that have won)
// If two boards win at the same time, the last one needs.
//
// We should mark all boards, though, and not return immediately, so that an early board winning
// We should mark all boards, and not return immediately, so that an early board winning
// does not ruin the winners for everyone else
winning_board = Some(board.clone());
//
// Also, more than one board can win in the same turn (I've seen it happen!)
winning_boards.push(board.clone());
// We could probably remove the board from the boards vec, but for debugging, this changes the
// indexes, which makes it difficult to follow the continuity of boards
@ -181,8 +181,8 @@ impl<'a> Iterator for BingoPlayer<'a> {
}
}
if let Some(winner) = winning_board {
return Some((call, winner));
if !winning_boards.is_empty() {
return Some((call, winning_boards));
}
}
@ -243,6 +243,15 @@ fn part1(input: &Input) -> u32 {
let (winning_call, winning_board) = game
.play()
.next()
.map(|(winning_call, winning_boards)| {
(
winning_call,
winning_boards
.into_iter()
.next()
.expect("Got back empty vec of winners, which shouldn't ever happen"),
)
})
.expect("Puzzle produced no winner for any bingo boards");
calculate_score(&winning_board, winning_call.into())
@ -253,6 +262,15 @@ fn part2(input: &Input) -> u32 {
let (winning_call, winning_board) = game
.play()
.last()
.map(|(winning_call, winning_boards)| {
(
winning_call,
winning_boards
.into_iter()
.last()
.expect("Got back empty vec of winners, which shouldn't ever happen"),
)
})
.expect("Puzzle produced no winner for any bingo boards");
calculate_score(&winning_board, winning_call.into())