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extern crate advent_of_code_2018;
use advent_of_code_2018::*;
use std::error::Error;
use std::path::PathBuf;
use std::cmp;
// cargo watch -cs "cargo run --release --bin day_5"
fn main() -> Result<(), Box<Error>> {
let input = read_file(&PathBuf::from("inputs/5.txt"))?;
//println!("Input: {:?}", input);
let polymer = {
let mut polymer: Vec<char> = input[0].chars().collect();
reduce(&mut polymer);
polymer
};
debug!(polymer.len());
let mut min_length = polymer.len();
for c in "abcdefghijklmnopqrstuvwxyz".chars() {
let mut polymer_without_char = polymer.clone();
polymer_without_char.retain(|x| x.to_ascii_lowercase() != c);
reduce(&mut polymer_without_char);
min_length = cmp::min(min_length, polymer_without_char.len());
}
debug!(min_length);
Ok(())
}
fn reduce(polymer: &mut Vec<char>) {
let mut had_reductions = true;
while had_reductions {
had_reductions = false;
for i in 0..polymer.len()-1 {
if polymer[i].to_ascii_lowercase() == polymer[i+1].to_ascii_lowercase() && polymer[i] != polymer[i+1] {
had_reductions = true;
polymer.remove(i+1);
polymer.remove(i);
// break isn't efficient, but does prevent indexing issues after removing
break;
}
}
}
}
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