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use std::{cmp::Reverse, collections::BTreeMap, str::FromStr};
use anyhow::Context;
use crate::{Problem, Solution};
pub struct Day07;
impl Problem for Day07 {
const DAY: u8 = 7;
const INPUT: &'static str = include_str!("../input/day_07.txt");
}
impl Solution for Day07 {
type Answer1 = usize;
type Answer2 = usize;
fn part_1(input: &str) -> anyhow::Result<Self::Answer1> {
let hand_bets = input
.lines()
.map(|s| {
s.trim()
.split_once(' ')
.with_context(|| format!("Invalid had format: {s}"))
.and_then(|(hand, bet)| anyhow::Ok((Reverse(hand.parse()?), bet.parse()?)))
})
.try_collect::<BTreeMap<Reverse<Hand<false>>, usize>>()?;
Ok(hand_bets
.into_values()
.enumerate()
.map(|(i, bid)| bid * (i + 1))
.sum())
}
fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
let hand_bets = input
.lines()
.map(|s| {
s.trim()
.split_once(' ')
.with_context(|| format!("Invalid had format: {s}"))
.and_then(|(hand, bet)| anyhow::Ok((Reverse(hand.parse()?), bet.parse()?)))
})
.try_collect::<BTreeMap<Reverse<Hand<true>>, usize>>()?;
Ok(hand_bets
.into_values()
.enumerate()
.map(|(i, bid)| bid * (i + 1))
.sum())
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
enum Hand<const WILD: bool> {
FiveOfAKind([Card<WILD>; 5]),
FourOfAKind([Card<WILD>; 5]),
FullHouse([Card<WILD>; 5]),
ThreeOfAKind([Card<WILD>; 5]),
TwoPair([Card<WILD>; 5]),
OnePair([Card<WILD>; 5]),
HighCard([Card<WILD>; 5]),
}
impl<const WILD: bool> Hand<WILD> {
fn count_types(mut cards: [Card<WILD>; 5]) -> (Vec<usize>, usize) {
cards.sort();
cards
.array_windows()
.rev()
.fold((Vec::from([1]), 0), |(mut acc, mut wilds), arr| {
match arr {
[Card::Joker, Card::Joker] if wilds == 0 => wilds += 1,
[_, Card::Joker] => wilds += 1,
[p, n] if p == n => *acc.last_mut().unwrap() += 1,
_ => acc.push(1),
}
(acc, wilds)
})
}
}
impl<const WILD: bool> From<[Card<WILD>; 5]> for Hand<WILD> {
fn from(cards: [Card<WILD>; 5]) -> Self {
let (mut counts, wilds) = Hand::count_types(cards);
counts.sort();
let n = counts.pop().unwrap();
let has_2 = counts.pop().is_some_and(|m| m == 2);
match (n + wilds).min(5) {
5 => Self::FiveOfAKind(cards),
4 => Self::FourOfAKind(cards),
3 if has_2 => Self::FullHouse(cards),
3 => Self::ThreeOfAKind(cards),
2 if has_2 => Self::TwoPair(cards),
2 => Self::OnePair(cards),
_ => Self::HighCard(cards),
}
}
}
impl<const WILD: bool> FromStr for Hand<WILD> {
type Err = anyhow::Error;
fn from_str(s: &str) -> Result<Self, Self::Err> {
let cards: [Card<WILD>; 5] = s
.chars()
.map(Card::try_from)
.try_collect::<Vec<_>>()?
.try_into()
.map_err(|v| anyhow::format_err!("Incorrect number of cards: {v:?}"))?;
Ok(Self::from(cards))
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
enum Card<const WILD: bool> {
Ace,
King,
Queen,
Jack,
Ten,
Nine,
Eight,
Seven,
Six,
Five,
Four,
Three,
Two,
Joker,
}
impl<const WILD: bool> TryFrom<char> for Card<WILD> {
type Error = anyhow::Error;
fn try_from(value: char) -> Result<Self, Self::Error> {
Ok(match value {
'A' => Card::Ace,
'K' => Card::King,
'Q' => Card::Queen,
'J' if WILD => Card::Joker,
'J' => Card::Jack,
'T' => Card::Ten,
'9' => Card::Nine,
'8' => Card::Eight,
'7' => Card::Seven,
'6' => Card::Six,
'5' => Card::Five,
'4' => Card::Four,
'3' => Card::Three,
'2' => Card::Two,
c => anyhow::bail!("Failed to parse card value: {c}"),
})
}
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = indoc::indoc! {"
32T3K 765
T55J5 684
KK677 28
KTJJT 220
QQQJA 483
"};
#[test]
fn test_part_1() -> anyhow::Result<()> {
Ok(assert_eq!(6440, Day07::part_1(INPUT)?))
}
#[test]
fn test_part_2() -> anyhow::Result<()> {
Ok(assert_eq!(5905, Day07::part_2(INPUT)?))
}
}
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