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day 7 solution

main
Andrew Coleman 2018-12-11 13:24:25 -05:00
parent 96a7927110
commit 7d193f50c2
3 changed files with 108 additions and 3 deletions

4
2018/day7/Cargo.lock generated Normal file
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[[package]]
name = "day7"
version = "0.1.0"

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