add 2023/12/2
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@ -1,12 +1,12 @@
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#![feature(test)]
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extern crate test;
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use aoc2023::{boilerplate, common::*};
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use fnv::FnvHashMap;
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use itertools::Itertools;
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use std::mem::transmute;
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use aoc2023::{boilerplate, common::*};
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use itertools::Itertools;
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const DAY: usize = 12;
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type I = u32;
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type I = usize;
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type Parsed<'a> = Vec<(&'a [Spring], Vec<I>)>;
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#[repr(u8)]
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@ -25,44 +25,104 @@ fn parse_input(raw: &str) -> Parsed {
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.collect()
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}
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fn is_legal(springs: &[Spring], expected: &[I]) -> bool {
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let broken = springs
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.iter()
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.map(|s| (s, 1))
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.coalesce(|(s1, n1), (s2, n2)| if s1 == s2 { Ok((s1, n1 + n2)) } else { Err(((s1, n1), (s2, n2))) })
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.filter_map(|(&s, n)| (s == Spring::Broken).then_some(n))
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.collect_vec();
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broken == expected
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}
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fn fill(springs: &mut Vec<Vec<Spring>>, base: Vec<Spring>, mut unknowns: Vec<usize>) {
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match unknowns.pop() {
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Some(i) => {
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let mut clone = base.clone();
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clone[i] = Spring::Operational;
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fill(springs, clone, unknowns.clone());
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let mut clone = base.clone();
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clone[i] = Spring::Broken;
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fill(springs, clone, unknowns.clone());
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}
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None => springs.push(base),
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}
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}
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fn part1(lines: &Parsed) -> usize {
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lines
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.iter()
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.map(|(springs, expected)| {
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let unknowns = springs.iter().enumerate().filter_map(|(i, s)| (s == &Spring::Unknown).then_some(i)).collect_vec();
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let mut buffer = Vec::with_capacity(1 << unknowns.len());
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fill(&mut buffer, springs.to_vec(), unknowns);
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buffer.iter().filter(|s| is_legal(s, expected)).count()
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let mut cache = FnvHashMap::default();
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valid_combinations_recursive(&springs, &expected, 0, 0, 0, 0, false, &mut cache)
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})
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.sum()
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}
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fn part2(_parsed: &Parsed) -> usize {
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unimplemented!()
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fn valid_combinations_recursive(
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springs: &[Spring],
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constraints: &[usize],
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index: usize,
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broken_count: usize,
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current_constraint: usize,
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broken_streak: usize,
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just_completed_streak: bool,
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cache: &mut FnvHashMap<(usize, usize, usize, usize, bool), usize>,
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) -> usize {
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if let Some(&cached) = cache.get(&(index, broken_count, current_constraint, broken_streak, just_completed_streak)) {
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return cached;
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}
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if index == springs.len() {
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let valid = broken_count == constraints.iter().sum::<usize>()
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&& current_constraint == constraints.len()
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&& (broken_streak == 0 || just_completed_streak);
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return valid as usize;
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}
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let valid = match springs[index] {
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Spring::Operational => {
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valid_combinations_recursive(springs, constraints, index + 1, broken_count, current_constraint, 0, false, cache)
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}
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Spring::Broken => {
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if current_constraint < constraints.len()
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&& broken_count < constraints.iter().take(current_constraint + 1).sum()
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&& !just_completed_streak
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{
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let just_completed_streak = broken_streak + 1 == constraints[current_constraint];
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valid_combinations_recursive(
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springs,
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constraints,
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index + 1,
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broken_count + 1,
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current_constraint + just_completed_streak as usize,
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broken_streak + 1,
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just_completed_streak,
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cache,
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)
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} else {
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0
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}
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}
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Spring::Unknown => {
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let operational =
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valid_combinations_recursive(springs, constraints, index + 1, broken_count, current_constraint, 0, false, cache);
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let broken = if current_constraint < constraints.len()
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&& broken_count < constraints.iter().take(current_constraint + 1).sum()
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&& !just_completed_streak
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{
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let just_completed_streak = broken_streak + 1 == constraints[current_constraint];
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valid_combinations_recursive(
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springs,
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constraints,
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index + 1,
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broken_count + 1,
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current_constraint + just_completed_streak as usize,
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broken_streak + 1,
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just_completed_streak,
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cache,
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)
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} else {
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0
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};
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operational + broken
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}
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};
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cache.insert((index, broken_count, current_constraint, broken_streak, just_completed_streak), valid);
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valid
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}
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fn part2(lines: &Parsed) -> usize {
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lines
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.iter()
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.map(|(springs, expected)| {
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let springs = springs.to_vec();
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let new_spring_length = springs.len() * 5 + 4;
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(
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springs.into_iter().chain(std::iter::once(Spring::Unknown)).cycle().take(new_spring_length).collect_vec(),
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expected.iter().cloned().cycle().take(expected.len() * 5).collect_vec(),
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)
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})
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.map(|(springs, expected)| {
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let mut cache = FnvHashMap::default();
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valid_combinations_recursive(&springs, &expected, 0, 0, 0, 0, false, &mut cache)
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})
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.sum()
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}
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boilerplate! {
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@ -75,9 +135,9 @@ boilerplate! {
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?###???????? 3,2,1",
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tests: {
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part1: { TEST_INPUT => 21 },
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part2: { TEST_INPUT => 0 },
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part2: { TEST_INPUT => 525152 },
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},
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bench1 == 7260,
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bench2 == 0,
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bench2 == 1909291258644,
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bench_parse: Vec::len => 1000,
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}
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