day 4 part 2

This commit is contained in:
Dominic 2023-12-04 10:59:19 +01:00
parent d618c30f3d
commit 4b0072f574
Signed by: msrd0
GPG key ID: DCC8C247452E98F9

View file

@ -2,16 +2,15 @@
use aoc23::read;
use chumsky::{prelude::*, text::int};
use std::collections::HashSet;
use std::collections::{BTreeMap, HashSet};
struct Card {
id: usize,
winning_nums: HashSet<usize>,
nums: HashSet<usize>
}
impl Card {
fn parser() -> impl Parser<char, Self, Error = Simple<char>> {
fn parser() -> impl Parser<char, (usize, Self), Error = Simple<char>> {
let nums = just(" ")
.repeated()
.ignore_then(int(10))
@ -29,36 +28,62 @@ impl Card {
.then(nums)
.then_ignore(just(" | "))
.then(nums)
.map(|((id, winning_nums), nums): ((String, _), _)| Self {
id: id.parse().unwrap(),
winning_nums,
nums
.map(|((id, winning_nums), nums): ((String, _), _)| {
(id.parse().unwrap(), Self { winning_nums, nums })
})
}
}
fn parser() -> impl Parser<char, Vec<Card>, Error = Simple<char>> {
fn parser() -> impl Parser<char, BTreeMap<usize, Card>, Error = Simple<char>> {
Card::parser()
.then_ignore(just("\n"))
.repeated()
.map(|cards| cards.into_iter().collect())
.then_ignore(end())
}
fn main() -> anyhow::Result<()> {
let cards = read("inputs/day4.txt", parser())?;
let mut points = 0;
for card in &cards {
let matches = card
.nums
let matches = cards
.iter()
.map(|(id, card)| {
(
*id,
card.nums
.iter()
.filter(|num| card.winning_nums.contains(num))
.count();
if matches > 0 {
points += 1 << (matches - 1);
.count()
)
})
.collect::<BTreeMap<usize, usize>>();
// part 1
println!(
"{}",
matches
.values()
.map(|count| match count {
0 => 0,
_ => 1 << (count - 1)
})
.sum::<usize>()
);
// part 2
let mut copies = cards
.keys()
.map(|key| (*key, 1))
.collect::<BTreeMap<usize, usize>>();
for id in cards.keys() {
let num_copies = copies[id];
for next in id + 1 ..= id + matches[id] {
if let Some(next_copies) = copies.get_mut(&next) {
*next_copies += num_copies;
}
}
println!("{points}");
}
println!("{}", copies.values().sum::<usize>());
Ok(())
}