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extern crate advent_of_code_2018;
use advent_of_code_2018::*;
use std::error::Error;
use std::path::PathBuf;
// cargo watch -cs "cargo run --release --bin day_14"
fn main() -> Result<(), Box<Error>> {
let input = 540561;
let scoreboard = find_ten_scoreboard_after(input);
println!("Result: ");
scoreboard.iter().for_each(|s| {
print!("{}", s);
});
println!();
let first_occurence = find_first_occurence_of(input);
debug!(first_occurence);
Ok(())
}
fn find_ten_scoreboard_after(input: usize) -> Vec<usize> {
let mut scoreboard = vec!(3,7);
let mut elf1_pos = 0;
let mut elf2_pos = 1;
while scoreboard.len() < (input + 10) {
let next = scoreboard[elf1_pos] + scoreboard[elf2_pos];
for digit in number_to_digits_vec(next) {
scoreboard.push(digit);
}
elf1_pos = (elf1_pos + 1 + scoreboard[elf1_pos]) % scoreboard.len();
elf2_pos = (elf2_pos + 1 + scoreboard[elf2_pos]) % scoreboard.len();
}
scoreboard.iter().skip(input).take(10).cloned().collect()
}
fn find_first_occurence_of(input: usize) -> usize {
let target_sequence = number_to_digits_vec(input);
debug!(target_sequence);
let mut scoreboard = vec!(3,7);
let mut elf1_pos = 0;
let mut elf2_pos = 1;
let mut target_index = None;
while target_index.is_none() {
let next = scoreboard[elf1_pos] + scoreboard[elf2_pos];
for digit in number_to_digits_vec(next) {
scoreboard.push(digit);
}
elf1_pos = (elf1_pos + 1 + scoreboard[elf1_pos]) % scoreboard.len();
elf2_pos = (elf2_pos + 1 + scoreboard[elf2_pos]) % scoreboard.len();
if scoreboard.len() >= target_sequence.len() + 2 {
for potential_target_index in scoreboard.len()-target_sequence.len()-2..scoreboard.len()-target_sequence.len()+1 {
let found = scoreboard.iter()
.skip(potential_target_index)
.take(target_sequence.len())
.zip(target_sequence.iter())
.all(|(a, b)| a == b);
if found {
target_index = Some(potential_target_index);
}
}
}
}
target_index.unwrap()
}
fn number_to_digits_vec(input: usize) -> Vec<usize> {
if input == 0 {
return vec!(0);
}
let mut result = Vec::new();
let mut acc = input;
while acc > 0 {
result.push(acc % 10);
acc /= 10;
}
result.reverse();
result
}
#[test]
fn vectorification() {
assert_eq!(number_to_digits_vec(10), vec!(1, 0));
assert_eq!(number_to_digits_vec(1), vec!(1));
assert_eq!(number_to_digits_vec(0), vec!(0));
}
#[test]
fn part1_examples() {
assert_eq!(find_ten_scoreboard_after(9), vec!(5,1,5,8,9,1,6,7,7,9));
assert_eq!(find_ten_scoreboard_after(2018), vec!(5,9,4,1,4,2,9,8,8,2));
}
#[test]
fn part2_examples() {
assert_eq!(find_first_occurence_of(51589), 9);
assert_eq!(find_first_occurence_of(59414), 2018);
}
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