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This commit is contained in:
nora 2023-12-03 15:24:42 +01:00
parent e80cf475a1
commit 485b24b202
2 changed files with 61 additions and 60 deletions
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62
2023/day03/src/lib.rs
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@ -1,6 +1,5 @@
mod p2faster_hash;
use std::collections::HashMap;
mod p2basic;
use helper::Day;
@ -16,7 +15,7 @@ helper::define_variants! {
basic => crate::part1;
}
part2 {
basic => crate::part2;
basic => crate::p2basic::part2;
fasher_hash => crate::p2faster_hash::part2;
}
}
@ -72,63 +71,6 @@ fn part1(input: &str) -> u64 {
acc
}
fn part2(input: &str) -> u64 {
fn contains_gear(s: &str) -> Option<usize> {
s.chars().position(|c| !c.is_ascii_digit() && c != '.')
}
let len = input.lines().next().unwrap().len();
let empty_border = std::iter::repeat('.').take(len).collect::<String>();
let mut prev2 = empty_border.as_str();
let mut prev1 = input.lines().next().unwrap();
let mut gears: HashMap<(usize, usize), Vec<u64>> = HashMap::new();
for (line_number, next) in input
.lines()
.skip(1)
.chain(Some(empty_border.as_str()))
.enumerate()
{
let mut numbers = prev1.char_indices().peekable();
while let Some((start, c)) = numbers.next() {
if c.is_ascii_digit() {
let mut end = start;
while let Some((idx, '0'..='9')) = numbers.next() {
end = idx;
}
let box_bounds = (start.saturating_sub(1))..std::cmp::min(end + 2, len);
let number = prev1[start..=end].parse::<u64>().unwrap();
if let Some(position) = contains_gear(&prev2[box_bounds.clone()]) {
let key = (line_number - 1, box_bounds.start + position);
gears.entry(key).or_default().push(number);
}
if let Some(position) = contains_gear(&prev1[box_bounds.clone()]) {
let key = (line_number, box_bounds.start + position);
gears.entry(key).or_default().push(number);
}
if let Some(position) = contains_gear(&next[box_bounds.clone()]) {
let key = (line_number + 1, box_bounds.start + position);
gears.entry(key).or_default().push(number);
}
}
}
prev2 = prev1;
prev1 = next;
}
gears
.values()
.filter(|v| v.len() == 2)
.map(|v| v[0] * v[1])
.sum()
}
helper::tests! {
day03 Day03;