108 lines
2.9 KiB
Rust
108 lines
2.9 KiB
Rust
use std::collections::{BTreeMap, HashMap};
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use std::fs::File;
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use std::io::{BufRead, BufReader};
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use std::iter::Iterator;
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type Day7Map = BTreeMap<char, Vec<char>>;
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fn print_map(steps: &Day7Map) {
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for (key, value) in steps {
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print!("{}: ", key);
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for val in value.iter() {
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print!("{} ", val);
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}
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println!("");
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}
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}
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fn calc_order(steps: &mut Day7Map) -> String {
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let mut first_available = '_';
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for (key, values) in steps.iter_mut() {
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if values.is_empty() {
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values.push('_');
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first_available = *key;
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break;
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}
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}
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let mut final_result = String::from("");
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if first_available == '_' {
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final_result
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} else {
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for (_key, values) in steps.iter_mut() {
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values.retain(|&x| x != first_available);
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}
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final_result.push(first_available);
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final_result.push_str(calc_order(steps).as_str());
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final_result
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}
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}
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fn calc_time(steps: &mut Day7Map, time_elapsed: i64, workers: &mut HashMap<char, i64>) -> i64 {
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let mut available: Vec<char> = Vec::new();
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// decrement workers
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for (_key, time_remaining) in workers.iter_mut() {
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*time_remaining -= 1;
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}
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// remove finished workers
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workers.retain(|&k, &mut count| {
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if count == 0 {
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for (_key, values) in steps.iter_mut() {
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values.retain(|&x| x != k);
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}
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false
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} else {
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true
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}
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});
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let mut needed_workers = 5 - workers.len();
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let mut needs_work = false;
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for (key, values) in steps.iter_mut() {
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if values.is_empty() {
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needs_work = true;
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if needed_workers > 0 {
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values.push('_');
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available.push(*key);
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needed_workers -= 1;
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if needed_workers == 0 {
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break;
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}
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}
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}
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}
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// return final sum of time
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if !needs_work && workers.is_empty() {
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return time_elapsed;
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}
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for new_step in available.iter() {
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// add new work
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workers.entry(*new_step).or_insert(*new_step as i64 - 4);
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}
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calc_time(steps, time_elapsed + 1, workers)
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}
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fn main() {
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let mut steps: Day7Map = BTreeMap::new();
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for line in BufReader::new(File::open("input").unwrap()).lines() {
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let line_str = line.unwrap();
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let mut chars = line_str.chars();
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let prereq = chars.nth(5).unwrap();
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let target = chars.nth(30).unwrap();
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steps
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.entry(target)
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.and_modify(|e| e.push(prereq))
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.or_insert(vec![prereq]);
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steps.entry(prereq).or_insert(vec![]);
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}
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print_map(&steps);
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let order = calc_order(&mut steps.clone());
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println!("final order: {}", order);
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let time = calc_time(&mut steps.clone(), 0, &mut HashMap::<char, i64>::new());
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println!("time required for 5 workers: {}", time);
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}
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