35 lines
1.1 KiB
Rust
35 lines
1.1 KiB
Rust
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use std::fs;
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use std::collections::HashSet;
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use std::collections::HashMap;
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use std::collections::BTreeSet;
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fn main() {
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let file = fs::read_to_string("input").expect("Unable to read file");
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let lines = file.split("\n").collect::<Vec<&str>>();
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let mut prerequisites = HashMap::<char, Vec<char>>::new();
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let mut queue = Vec::new();
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for line in lines{
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let words: Vec<char> = line.chars().collect();
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prerequisites.entry(words[36] as char).or_default().push(words[5]);
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prerequisites.entry(words[5]).or_default();
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}
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let mut todo = prerequisites.keys().cloned().collect::<BTreeSet<_>>();
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let mut prereq_done = HashSet::new();
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while !todo.is_empty() {
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for c in todo.clone().into_iter() {
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if prerequisites.get(&c).is_none() || prerequisites.get(&c).unwrap().into_iter().all(|prerequisit| prereq_done.contains(prerequisit)){
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queue.push(c);
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prereq_done.insert(c);
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todo.remove(&c);
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break;
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}
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}
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}
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println!("{}", queue.into_iter().collect::<String>());
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}
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