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Prepare for part 2

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This commit is contained in:
Bert Peters
2023-12-18 20:32:15 +01:00
parent f15c8fbec3
commit 8faabf1220
2 changed files with 15 additions and 21 deletions
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2
2023/src/day12.rs
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@@ -33,7 +33,7 @@ fn number_ways(line: &[u8], groups: &[u8]) -> u64 {
// Either defective or maybe defective
if c != b'.' && cur_group < usize::from(group) {
next[group_pos * group_stride + cur_group as usize + 1] += ways;
next[group_pos * group_stride + cur_group + 1] += ways;
}
if c != b'#' {

34
2023/src/day18.rs
View File

@@ -1,10 +1,8 @@
use nom::bytes::complete::tag;
use nom::bytes::complete::take;
use nom::bytes::complete::take_while1;
use nom::combinator::map;
use nom::combinator::map_res;
use nom::multi::many1;
use nom::sequence::delimited;
use nom::sequence::pair;
use nom::sequence::terminated;
use nom::IResult;
@@ -17,8 +15,8 @@ struct Dig {
amount: u64,
}
fn parse_instructions(i: &[u8]) -> IResult<&[u8], Vec<(Dig, u64)>> {
many1(pair(
fn parse_instructions(i: &[u8]) -> IResult<&[u8], Vec<Dig>> {
many1(terminated(
map(
pair(
terminated(
@@ -37,24 +35,18 @@ fn parse_instructions(i: &[u8]) -> IResult<&[u8], Vec<(Dig, u64)>> {
),
|(dir, amount)| Dig { dir, amount },
),
delimited(
tag("(#"),
map_res(take_while1(nom::character::is_hex_digit), |s| {
u64::from_str_radix(std::str::from_utf8(s).expect("Checked hex digits"), 16)
}),
tag(")\n"),
),
take(10usize),
))(i)
}
fn compute_points(instructions: &[(Dig, u64)]) -> Vec<(i64, i64)> {
fn compute_points(instructions: &[Dig]) -> Vec<(i64, i64)> {
let mut result = Vec::with_capacity(instructions.len() + 1);
result.push((0, 0));
let mut x = 0;
let mut y = 0;
for &(Dig { dir, amount }, _) in instructions {
for &Dig { dir, amount } in instructions {
match dir {
Direction::Up => y -= amount as i64,
Direction::Left => x -= amount as i64,
@@ -78,22 +70,24 @@ fn shoelace(points: &[(i64, i64)]) -> i64 {
/ 2
}
pub fn part1(input: &[u8]) -> anyhow::Result<String> {
let instructions = parse_input(input, parse_instructions)?;
let points = compute_points(&instructions);
fn solve(digs: &[Dig]) -> anyhow::Result<String> {
let points = compute_points(digs);
let area = shoelace(&points);
// Assumption: we don't cross over ourselves
let perimeter = instructions
.iter()
.map(|(dig, _)| dig.amount as i64)
.sum::<i64>();
let perimeter = digs.iter().map(|dig| dig.amount as i64).sum::<i64>();
let total = area + perimeter / 2 + 1;
Ok(total.to_string())
}
pub fn part1(input: &[u8]) -> anyhow::Result<String> {
let digs = parse_input(input, parse_instructions)?;
solve(&digs)
}
pub fn part2(_input: &[u8]) -> anyhow::Result<String> {
anyhow::bail!("Not implemented")
}