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|
use advent_lib::prelude::*;
use std::collections::BTreeMap;
//use std::convert::TryFrom;
#[derive(Clone,Debug)]
enum Rule {
Alternatives(Vec<Vec<i64>>),
Character(char),
}
fn main() -> Result<()> {
let mut args = std::env::args();
if args.len() != 2 {
eprintln!("Usage: advent input");
}
let _ = args.next();
let filename = args.next().unwrap();
let input = advent_lib::read_lines_file(&filename)?;
let input = advent_lib::group_lines_by_blanks(input);
let mut rules: BTreeMap<i64,Rule> = BTreeMap::new();
for line in &input[0] {
let colon_point = line.find(':').unwrap();
let (rule_number, rest) = line.split_at(colon_point);
let rule_number = rule_number.parse::<i64>().unwrap();
let (_, rest) = rest.split_at(2);
let words: Vec<&str> = rest.split(' ').collect();
let mut chars = words[0].chars();
if words.len() == 1 && chars.next() == Some('"') {
let c = chars.next().unwrap();
rules.insert(rule_number, Rule::Character(c));
} else {
let alternatives_inputs = words.split(|word| *word == "|");
let mut alternatives: Vec<Vec<i64>> = Vec::new();
for alternative_words in alternatives_inputs {
let mut alternative: Vec<i64> = Vec::new();
for word in alternative_words {
alternative.push(word.parse::<i64>().unwrap());
}
alternatives.push(alternative);
}
rules.insert(rule_number, Rule::Alternatives(alternatives));
}
}
let mut match_count = 0;
for line in &input[1] {
if is_match(&rules, 0, line) {
match_count += 1;
}
}
println!("{:?}", match_count);
rules.insert(8, Rule::Alternatives(vec![vec![42], vec![42, 8]]));
rules.insert(11, Rule::Alternatives(vec![vec![42, 31], vec![42, 11, 31]]));
let mut match_count = 0;
for line in &input[1] {
if is_match(&rules, 0, line) {
match_count += 1;
}
}
println!("{:?}", match_count);
Ok(())
}
fn is_match(rules: &BTreeMap<i64,Rule>, root_rule: i64, input: &str) -> bool {
let match_results = is_match_helper(rules, root_rule, input);
for rest in match_results {
if rest.len() == 0 {
return true;
}
}
false
}
fn is_match_helper<'a>(rules: &BTreeMap<i64,Rule>, root_rule: i64, input: &'a str)
-> Vec<&'a str>
{
let mut results = Vec::new();
match rules.get(&root_rule).unwrap() {
Rule::Alternatives(alternatives) => {
for alternative in alternatives {
let mut possible_rests = Vec::new();
possible_rests.push(input);
for sub_rule in alternative {
let mut new_possible_rests = Vec::new();
for rest in possible_rests {
let sub_matches = is_match_helper(rules, *sub_rule, rest);
for new_rest in sub_matches {
new_possible_rests.push(new_rest);
}
}
possible_rests = new_possible_rests;
}
for rest in possible_rests {
results.push(rest);
}
}
},
Rule::Character(character) => {
if input.len() >= 1 && input.chars().next() == Some(*character) {
let (_, rest) = input.split_at(1);
results.push(rest);
}
},
}
results
}
|