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#![allow(dead_code)]
#[macro_use] extern crate ad_hoc_iter;
#[macro_use] extern crate cfg_if;
use std::{
io,
io::BufReader,
fs::OpenOptions,
num::NonZeroU8,
ops,
iter,
iter::Sum,
};
use smallmap::Map;
mod input;
mod diff;
use diff::Diffs;
const INPUT: &str = "input";
type Adaptors = Map<NonZeroU8, ()>;
fn parse_input(file: &str) -> Result<impl Iterator<Item = input::Int>, io::Error>
{
let file = OpenOptions::new().read(true).open(file)?;
Ok(input::read_input(BufReader::new(file)))
}
fn find_smallest(map: &Adaptors, finding: impl Into<u8>) -> (Option<u8>, Diffs)
{
#![allow(unused_assignments)]
let finding = finding.into();
let mut diffs = Diffs::default();
let mut set=false;
macro_rules! find {
($l:literal) => {
{
let shim = finding + $l;
debug_assert!(shim > 0);
match map.get(&unsafe {
NonZeroU8::new_unchecked(shim)
}).map(|_| shim) {
Some(yes) if !set => {
set = true;
*diffs.at_mut($l-1) += 1;
Some(yes)
},
x => x
}
}
}
};
(iter![
find!(1),
find!(2),
find!(3)
].filter_map(std::convert::identity)
.min(), diffs)
}
#[inline(always)] fn conv_input(input: impl Iterator<Item=input::Int>) -> impl Iterator<Item = (NonZeroU8, ())>
{
input.filter_map(NonZeroU8::new).zip(iter::repeat(()))
}
#[inline(always)] fn get_input() -> impl Iterator<Item=input::Int>
{
cfg_if!{
if #[cfg(feature="test")] {
input::test_input()
} else {
parse_input(INPUT).unwrap()
}
}
}
fn main() -> Result<(), Box<dyn std::error::Error>>
{
let all_jolts = {
let mut map: Adaptors = conv_input(get_input()).collect();
unsafe {
map.insert(NonZeroU8::new_unchecked(map.iter().map(|&(x, _)| x).max().unwrap().get() + 3), ());
}
map
};
debug_assert_eq!(all_jolts.num_pages(), 1); // Assert we have space efficiency.
let diffs: Diffs = std::iter::successors(Some((0, Diffs::default())), |&(next, _)| {
if let (Some(next), d) = find_smallest(&all_jolts, next) {
Some((next, d))
} else {
None
}
}).map(|(_, d)| d).sum();
println!("{}", diffs.jd1() * diffs.jd3());
Ok(())
}