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day19.rs
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use crate::data::load;
use regex::Regex;
use std::{collections::HashMap, num::ParseIntError};
use thiserror::Error;
#[derive(Error, Debug, PartialEq, Eq)]
pub enum PuzzleErr {
#[error("Input parsing error: {}.", .0)]
ParseInputError(String),
#[error("Integer parsing error: {:?}.", .0)]
ParseIntError(#[from] ParseIntError),
#[error("Not yet implemented.")]
NotImplemented,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct Part {
x: u32,
m: u32,
a: u32,
s: u32,
}
impl TryFrom<&str> for Part {
type Error = PuzzleErr;
fn try_from(value: &str) -> Result<Self, Self::Error> {
let re = Regex::new(r"x=(?<x>\d+),m=(?<m>\d+),a=(?<a>\d+),s=(?<s>\d+)").unwrap();
let Some(caps) = re.captures(value) else {
return Err(PuzzleErr::ParseInputError(value.to_string()));
};
Ok(Self {
x: caps["x"].parse()?,
m: caps["m"].parse()?,
a: caps["a"].parse()?,
s: caps["s"].parse()?,
})
}
}
impl Part {
fn sum(&self) -> u32 {
self.x + self.a + self.m + self.s
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum RuleResult {
A,
R,
W(String),
}
impl From<&str> for RuleResult {
fn from(value: &str) -> Self {
match value {
"A" => Self::A,
"R" => Self::R,
x => Self::W(x.to_string()),
}
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum CompOp {
Greater,
Less,
}
impl TryFrom<&str> for CompOp {
type Error = PuzzleErr;
fn try_from(value: &str) -> Result<Self, Self::Error> {
match value {
"<" => Ok(CompOp::Less),
">" => Ok(CompOp::Greater),
_ => Err(PuzzleErr::ParseInputError(value.to_string())),
}
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum PartComponent {
X,
M,
A,
S,
}
impl TryFrom<&str> for PartComponent {
type Error = PuzzleErr;
fn try_from(value: &str) -> Result<Self, Self::Error> {
match value {
"x" => Ok(PartComponent::X),
"m" => Ok(PartComponent::M),
"a" => Ok(PartComponent::A),
"s" => Ok(PartComponent::S),
_ => Err(PuzzleErr::ParseInputError(value.to_string())),
}
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
struct ComparisonOperation {
var_name: PartComponent,
op: CompOp,
value: u32,
}
impl ComparisonOperation {
fn execute(&self, part: &Part) -> bool {
let part_val = match self.var_name {
PartComponent::X => part.x,
PartComponent::M => part.m,
PartComponent::A => part.a,
PartComponent::S => part.s,
};
match self.op {
CompOp::Greater => part_val > self.value,
CompOp::Less => part_val < self.value,
}
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
enum Rule {
Comparison {
op: ComparisonOperation,
res: RuleResult,
},
Simple(RuleResult),
}
impl Rule {
fn execute(&self, part: &Part) -> Option<RuleResult> {
match self {
Rule::Simple(res) => Some(res.clone()),
Rule::Comparison { op, res } => {
if op.execute(part) {
Some(res.clone())
} else {
None
}
}
}
}
}
impl TryFrom<&str> for Rule {
type Error = PuzzleErr;
fn try_from(value: &str) -> Result<Self, Self::Error> {
if !(value.contains('<') | value.contains('>')) {
let res = RuleResult::from(value);
return Ok(Rule::Simple(res));
}
// a<2006:qkq
let re =
Regex::new(r"(?<var_name>\w)(?<op_name>[<|>])(?<value>\d+):(?<res_name>\w+)").unwrap();
let Some(caps) = re.captures(value) else {
return Err(PuzzleErr::ParseInputError(value.to_string()));
};
let op = ComparisonOperation {
var_name: PartComponent::try_from(&caps["var_name"])?,
op: CompOp::try_from(&caps["op_name"])?,
value: caps["value"].parse()?,
};
let res = RuleResult::from(&caps["res_name"]);
Ok(Rule::Comparison { op, res })
}
}
#[derive(Debug, Clone, PartialEq, Eq)]
struct Workflow {
name: String,
rules: Vec<Rule>,
}
impl TryFrom<&str> for Workflow {
type Error = PuzzleErr;
fn try_from(value: &str) -> Result<Self, Self::Error> {
let re = Regex::new(r"^(?<name>\w+)\{(?<rules>.+)\}").unwrap();
let Some(caps) = re.captures(value) else {
return Err(PuzzleErr::ParseInputError(value.to_string()));
};
let rules = &caps["rules"]
.split(',')
.map(Rule::try_from)
.collect::<Result<Vec<Rule>, PuzzleErr>>()?;
Ok(Self {
name: caps["name"].to_string(),
rules: rules.clone(),
})
}
}
impl Workflow {
fn execute(&self, part: &Part) -> RuleResult {
for rule in self.rules.iter() {
if let Some(res) = rule.execute(part) {
return res;
}
}
unreachable!();
}
}
fn parse_workflows(input: &str) -> Result<Vec<Workflow>, PuzzleErr> {
input
.trim()
.lines()
.map(Workflow::try_from)
.collect::<Result<Vec<Workflow>, PuzzleErr>>()
}
fn parse_parts(input: &str) -> Result<Vec<Part>, PuzzleErr> {
input
.trim()
.lines()
.map(Part::try_from)
.collect::<Result<Vec<Part>, PuzzleErr>>()
}
fn parse_input(input: &str) -> Result<(Vec<Workflow>, Vec<Part>), PuzzleErr> {
let split_input = input.trim().split("\n\n").collect::<Vec<_>>();
let workflows = parse_workflows(split_input[0])?;
let parts = parse_parts(split_input[1])?;
Ok((workflows, parts))
}
fn organize_part(part: &Part, workflows: &HashMap<&str, Workflow>) -> RuleResult {
let mut workflow_name = "in".to_string();
loop {
let w: &Workflow = workflows.get(workflow_name.as_str()).unwrap();
let res = w.execute(part);
workflow_name = match res {
RuleResult::A | RuleResult::R => return res,
RuleResult::W(next_w) => next_w,
};
}
}
fn organize_parts(parts: &[Part], workflows: &HashMap<&str, Workflow>) -> u32 {
parts
.iter()
.filter_map(|p| {
if organize_part(p, workflows) == RuleResult::A {
Some(p.sum())
} else {
None
}
})
.sum()
}
pub fn puzzle_1(input: &str) -> Result<u32, PuzzleErr> {
let (workflows, parts) = parse_input(input)?;
let workflows_map = workflows
.iter()
.map(|w| (w.name.as_str(), w.clone()))
.collect::<HashMap<&str, Workflow>>();
Ok(organize_parts(&parts, &workflows_map))
}
pub fn puzzle_2(input: &str) -> Result<u32, PuzzleErr> {
let (workflows, parts) = parse_input(input)?;
let workflows_map = workflows
.iter()
.map(|w| (w.name.as_str(), w.clone()))
.collect::<HashMap<&str, Workflow>>();
Ok(organize_parts(&parts, &workflows_map))
}
pub fn main(data_dir: &str) {
println!("Day 19: Aplenty");
let data = load(data_dir, 19, None);
// Puzzle 1.
let answer_1 = puzzle_1(&data);
match answer_1 {
Ok(x) => println!(" Puzzle 1: {}", x),
Err(e) => panic!("No solution to puzzle 1: {}.", e),
}
assert_eq!(answer_1, Ok(509597));
// Puzzle 2.
// let answer_2 = puzzle_2(&data);
// match answer_2 {
// Ok(x) => println!(" Puzzle 2: {}", x),
// Err(e) => panic!("No solution to puzzle 2: {}", e),
// }
// assert_eq!(answer_2, Ok(30449))
}