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day12 solution. gross.

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Andrew Coleman 2023-12-13 13:47:53 -05:00
parent a985a81d6d
commit e6cf50fb47
2 changed files with 209 additions and 0 deletions

208
2023/src/day12.rs Normal file
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@ -0,0 +1,208 @@
use aoc_runner_derive::{aoc, aoc_generator};
use std::collections::HashMap;
use std::str::FromStr;
type Cache = HashMap<(Vec<Condition>, Vec<usize>), usize>;
#[derive(Copy, Clone, Eq, PartialEq, Hash)]
enum Condition {
Unknown,
Functional,
Damaged,
}
impl FromStr for Condition {
type Err = String;
fn from_str(input: &str) -> Result<Condition, Self::Err> {
match input {
"?" => Ok(Condition::Unknown),
"." => Ok(Condition::Functional),
"#" => Ok(Condition::Damaged),
n @ _ => Err(format!("Unknown character '{}'", n)),
}
}
}
#[derive(Clone)]
struct Spring {
list: Vec<Condition>,
groups: Vec<usize>,
}
#[aoc_generator(day12)]
fn parse(input: &str) -> Vec<Spring> {
input
.lines()
.filter_map(|line| {
if !line.is_empty() {
let parts = line.split(" ").collect::<Vec<&str>>();
let list = parts[0]
.split("")
.filter_map(|e| {
if e.is_empty() {
None
} else {
Condition::from_str(e).ok()
}
})
.collect();
let groups = parts[1]
.split(",")
.map(|e| e.parse::<usize>().unwrap())
.collect();
Some(Spring { list, groups })
} else {
None
}
})
.collect()
}
fn calc_solutions(list: &Vec<Condition>, groups: &Vec<usize>, cache: &mut Cache) -> usize {
if list.is_empty() {
if groups.is_empty() {
return 1;
} else {
return 0;
}
}
match list[0] {
Condition::Functional => calc_solutions(&list[1..].to_vec(), groups, cache),
Condition::Damaged => calc_damaged_solutions(list, groups, cache),
Condition::Unknown => {
calc_solutions(&list[1..].to_vec(), groups, cache)
+ calc_damaged_solutions(list, groups, cache)
}
}
}
fn calc_damaged_solutions(list: &Vec<Condition>, groups: &Vec<usize>, cache: &mut Cache) -> usize {
if let Some(&result) = cache.get(&(list.clone(), groups.clone())) {
return result;
}
if groups.is_empty() {
return 0;
}
if list.len() < groups[0] {
return 0;
}
for i in 0..groups[0] {
if list[i] == Condition::Functional {
return 0;
}
}
if list.len() == groups[0] {
if groups.len() == 1 {
return 1;
}
return 0;
}
if list[groups[0]] == Condition::Damaged {
return 0;
}
let result = calc_solutions(
&list[(groups[0] + 1)..].to_vec(),
&groups[1..].to_vec(),
cache,
);
cache.insert((list.clone(), groups.clone()), result);
result
}
#[aoc(day12, part1)]
fn part1(input: &[Spring]) -> usize {
let mut result: usize = 0;
for src in input.iter() {
let mut cache: Cache = HashMap::new();
result += calc_solutions(&src.list, &src.groups, &mut cache);
}
result
}
#[aoc(day12, part2)]
fn part2(input: &[Spring]) -> usize {
let mut result: usize = 0;
for src in input.iter() {
let mut l: Vec<Condition> = Vec::with_capacity(src.groups.len() * 5 + 5);
let mut g: Vec<usize> = Vec::with_capacity(src.list.len() * 5);
for index in 0..5 {
l.append(&mut src.list.clone());
if index < 4 {
l.push(Condition::Unknown);
}
g.append(&mut src.groups.clone());
}
let mut cache: Cache = HashMap::new();
let s = calc_solutions(&l, &g, &mut cache);
result += s;
}
result
}
#[cfg(test)]
mod tests {
use super::*;
const SAMPLE_DATA: &'static str = r#"???.### 1,1,3
.??..??...?##. 1,1,3
?#?#?#?#?#?#?#? 1,3,1,6
????.#...#... 4,1,1
????.######..#####. 1,6,5
?###???????? 3,2,1
"#;
#[test]
fn sample_data_part1() {
let input = parse(&SAMPLE_DATA);
assert_eq!(part1(&input), 21);
}
#[test]
fn sample_data_3() {
let line1 = Spring {
list: vec![
Condition::Unknown,
Condition::Unknown,
Condition::Unknown,
Condition::Functional,
Condition::Damaged,
Condition::Damaged,
Condition::Damaged,
],
groups: vec![1, 1, 3],
};
assert_eq!(part2(&[line1]), 1);
let line2 = Spring {
list: vec![
Condition::Functional,
Condition::Unknown,
Condition::Unknown,
Condition::Functional,
Condition::Functional,
Condition::Unknown,
Condition::Unknown,
Condition::Functional,
Condition::Functional,
Condition::Functional,
Condition::Unknown,
Condition::Damaged,
Condition::Damaged,
Condition::Functional,
],
groups: vec![1, 1, 3],
};
assert_eq!(part2(&[line2]), 16384);
}
#[test]
fn sample_data_part2() {
let input = parse(&SAMPLE_DATA);
assert_eq!(part2(&input), 525152);
}
}

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@ -11,5 +11,6 @@ mod day08;
mod day09;
mod day10;
mod day11;
mod day12;
aoc_lib! { year = 2023 }