diff options
| -rw-r--r-- | src/bin/day19.rs | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/src/bin/day19.rs b/src/bin/day19.rs new file mode 100644 index 0000000..89eb7dd --- /dev/null +++ b/src/bin/day19.rs @@ -0,0 +1,194 @@ +use std::collections::HashMap; + +static DAY: u8 = 19; + +fn main() { + let input = advent::read_lines(DAY); + println!("{DAY}a: {}", rating_numbers(&input)); + println!("{DAY}b: {}", 0); +} + +#[derive(Clone)] +enum WorkflowResult { + Accept, + Reject, + NextWorkflow(String), +} + +impl WorkflowResult { + fn from(input: &str) -> WorkflowResult { + match input { + "A" => WorkflowResult::Accept, + "R" => WorkflowResult::Reject, + next => WorkflowResult::NextWorkflow(next.to_string()), + } + } +} + +enum Rule { + CmpGt(char, u32, WorkflowResult), + CmpLt(char, u32, WorkflowResult), + Result(WorkflowResult), +} + +impl Rule { + fn new(input: &str) -> Rule { + if input.contains('<') { + let tokens = input.split(|x| x == '<' || x == ':').collect::<Vec<_>>(); + let c = tokens[0].chars().next().unwrap(); + let val = tokens[1].parse().unwrap(); + let result = WorkflowResult::from(tokens[2]); + Rule::CmpLt(c, val, result) + } else if input.contains('>') { + let tokens = input.split(|x| x == '>' || x == ':').collect::<Vec<_>>(); + let c = tokens[0].chars().next().unwrap(); + let val = tokens[1].parse().unwrap(); + let result = WorkflowResult::from(tokens[2]); + Rule::CmpGt(c, val, result) + } else { + Rule::Result(WorkflowResult::from(input)) + } + } + + fn matches(&self, xmas: &XmasValues) -> Option<WorkflowResult> { + match self { + Rule::CmpGt(variable, value, result) => match variable { + 'x' => if xmas.x > *value { Some(result.clone()) } else { None }, + 'm' => if xmas.m > *value { Some(result.clone()) } else { None }, + 'a' => if xmas.a > *value { Some(result.clone()) } else { None }, + 's' => if xmas.s > *value { Some(result.clone()) } else { None }, + _ => panic!("invalid char"), + }, + Rule::CmpLt(variable, value, result) => match variable { + 'x' => if xmas.x < *value { Some(result.clone()) } else { None }, + 'm' => if xmas.m < *value { Some(result.clone()) } else { None }, + 'a' => if xmas.a < *value { Some(result.clone()) } else { None }, + 's' => if xmas.s < *value { Some(result.clone()) } else { None }, + _ => panic!("invalid char"), + } + Rule::Result(result) => Some(result.clone()), + } + } +} + +struct Workflow { + name: String, + rules: Vec<Rule>, +} + +impl Workflow { + fn new(input: &str) -> Workflow { + let (name, rules_str) = input[0..input.len() - 1].split_once('{').unwrap(); + let rules = rules_str.split(',') + .map(Rule::new) + .collect::<Vec<_>>(); + let name = name.to_string(); + + Workflow { name, rules } + } + + fn matches(&self, xmas: &XmasValues) -> WorkflowResult { + for rule in &self.rules { + if let Some(result) = rule.matches(xmas) { + return result.clone(); + } + } + panic!("no matching rule found"); + } +} + +struct XmasValues { + x: u32, + m: u32, + a: u32, + s: u32, +} + +impl XmasValues { + fn new(input: &str) -> XmasValues { + let mut xmas = XmasValues { x: 0, m: 0, a: 0, s: 0 }; + for string in input[1 .. input.len() - 1 ].split(',') { + let (variable, value) = string.split_once('=').unwrap(); + let value = value.parse::<u32>().unwrap(); + match variable { + "x" => xmas.x = value, + "m" => xmas.m = value, + "a" => xmas.a = value, + "s" => xmas.s = value, + _ => panic!("invalid variable"), + } + } + xmas + } + + fn rating(&self) -> u32 { + self.x + self.m + self.a + self.s + } +} + +struct Workflows { + workflows: HashMap<String, Workflow>, +} + +impl Workflows { + fn new(input: &[String]) -> Workflows { + let workflows = input.iter() + .map(|workflow| Workflow::new(workflow)) + .map(|workflow| (workflow.name.clone(), workflow)) + .collect(); + Workflows { workflows } + } + + fn is_accepted(&self, xmas: &XmasValues) -> bool { + let mut workflow = &self.workflows["in"]; + loop { + match workflow.matches(xmas) { + WorkflowResult::Accept => return true, + WorkflowResult::Reject => return false, + WorkflowResult::NextWorkflow(next) => workflow = &self.workflows[&next], + } + } + } +} + +fn rating_numbers(input: &[String]) -> u32 { + let blocks = input.split(|line| line.is_empty()).collect::<Vec<_>>(); + let (workflows, values) = (Workflows::new(blocks[0]), blocks[1]); + let values = values.iter() + .map(|value| XmasValues::new(value)) + .collect::<Vec<_>>(); + + values.iter() + .filter(|&value| workflows.is_accepted(value)) + .map(|value| value.rating()) + .sum() +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn test() { + let input = [ + "px{a<2006:qkq,m>2090:A,rfg}", + "pv{a>1716:R,A}", + "lnx{m>1548:A,A}", + "rfg{s<537:gd,x>2440:R,A}", + "qs{s>3448:A,lnx}", + "qkq{x<1416:A,crn}", + "crn{x>2662:A,R}", + "in{s<1351:px,qqz}", + "qqz{s>2770:qs,m<1801:hdj,R}", + "gd{a>3333:R,R}", + "hdj{m>838:A,pv}", + "", + "{x=787,m=2655,a=1222,s=2876}", + "{x=1679,m=44,a=2067,s=496}", + "{x=2036,m=264,a=79,s=2244}", + "{x=2461,m=1339,a=466,s=291}", + "{x=2127,m=1623,a=2188,s=1013}", + ].iter().map(|&x| String::from(x)).collect::<Vec<_>>(); + assert_eq!(rating_numbers(&input), 19114); + } +} |