Day 12
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@ -0,0 +1,306 @@
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use std::collections::HashMap;
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pub fn run() {
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let input = include_str!("../input/day12.txt");
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// let input = r#"???.### 1,1,3
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// .??..??...?##. 1,1,3
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// ?#?#?#?#?#?#?#? 1,3,1,6
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// ????.#...#... 4,1,1
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// ????.######..#####. 1,6,5
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// ?###???????? 3,2,1"#;
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let mut lines = input
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.trim()
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.lines()
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.map(|l| parse_line(l))
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.collect::<Vec<_>>();
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let count_sum = lines
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.iter()
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.map(|(cs, runs)| {
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count_arrangements(
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CountInputs {
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cs: &cs,
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assuming_first_char: None,
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in_run: false,
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runs: runs.clone(),
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},
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&mut HashMap::new(),
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)
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})
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.sum::<usize>();
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dbg!(count_sum);
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for l in lines.iter_mut() {
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unfold_line(&mut l.0, &mut l.1);
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}
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let count_sum2 = lines
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.iter()
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.map(|(cs, runs)| {
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let res = count_arrangements(
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CountInputs {
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cs: &cs,
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assuming_first_char: None,
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in_run: false,
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runs: runs.clone(),
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},
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&mut HashMap::new(),
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);
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println!("finished line");
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res
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})
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.sum::<usize>();
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dbg!(count_sum2);
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}
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fn parse_line(s: &str) -> (Vec<char>, Vec<u8>) {
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let (l, r) = s.trim().split_once(" ").unwrap();
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(
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l.chars().collect(),
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r.split(",").map(|s| s.parse().unwrap()).collect(),
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)
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}
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fn unfold_line(cs: &mut Vec<char>, runs: &mut Vec<u8>) {
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let orig_cs = cs.to_vec();
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let orig_runs = runs.to_vec();
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for _ in 0..4 {
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cs.push('?');
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cs.extend(orig_cs.iter());
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runs.extend(orig_runs.iter());
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}
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}
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#[derive(Debug, Clone, PartialEq, Eq, Hash)]
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struct CountInputs<'a> {
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cs: &'a [char],
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assuming_first_char: Option<char>,
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in_run: bool,
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runs: Vec<u8>,
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}
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fn count_arrangements<'a: 'b, 'b>(
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inputs: CountInputs<'a>,
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// cs: &[char],
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// assuming_first_char: Option<char>,
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// // mut accepted: Vec<char>,
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// in_run: bool,
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// runs: &[u8],
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cache: &mut HashMap<CountInputs<'b>, usize>,
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) -> usize {
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if let Some(result) = cache.get(&inputs) {
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return *result;
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}
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if inputs.runs.is_empty() {
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assert!(!inputs.in_run);
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for &c in inputs.cs {
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if c == '#' {
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// invalid, since there are remaining broken springs with no broken runs
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cache.insert(inputs, 0);
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return 0;
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} else {
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// accepted.push('.');
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}
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}
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// valid
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// println!("{}", accepted.iter().collect::<String>());
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cache.insert(inputs, 1);
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return 1;
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}
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if inputs.cs.is_empty() {
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// if we're out of chars, valid iff there are no runs remaining
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if inputs.runs.is_empty() {
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assert!(!inputs.in_run);
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cache.insert(inputs, 1);
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return 1;
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} else {
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cache.insert(inputs, 0);
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return 0;
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}
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}
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let first = inputs.assuming_first_char.unwrap_or(inputs.cs[0]);
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if first == '#' {
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if inputs.runs[0] == 1 {
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// current run should be finished
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if inputs.cs.len() > 1 {
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if inputs.cs[1] == '#' {
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// if the next char is #, invalid b/c the current run would continue
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return 0;
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} else if inputs.cs[1] == '.' || inputs.cs[1] == '?' {
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// let mut accepted = accepted.to_vec();
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// accepted.push('#');
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// accepted.push('.');
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// current run does indeed end
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return count_arrangements(
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CountInputs {
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cs: &inputs.cs[2..],
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assuming_first_char: None,
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in_run: false,
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runs: inputs.runs[1..].iter().copied().collect::<Vec<_>>(),
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},
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cache,
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);
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} else {
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panic!("invalid char {}", inputs.cs[1]);
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}
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} else {
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// end of string, valid iff there are no more runs
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if inputs.runs.len() == 1 {
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// println!(
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// "{}#, last run: {}",
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// accepted.iter().collect::<String>(),
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// runs[0]
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// );
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cache.insert(inputs, 1);
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return 1;
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} else {
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cache.insert(inputs, 0);
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return 0;
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}
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}
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} else {
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// accepted.push('#');
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// current run continues
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let mut runs_copy = inputs.runs.to_vec();
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runs_copy[0] -= 1;
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// println!(
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// "{}, current run continuing, {:?}",
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// accepted.iter().collect::<String>(),
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// runs_copy
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// );
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return count_arrangements(
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CountInputs {
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cs: &inputs.cs[1..],
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assuming_first_char: None,
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in_run: true,
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runs: runs_copy,
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},
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cache,
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);
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}
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} else if first == '?' {
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// let mut accepted_dot = accepted.clone();
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// accepted_dot.push('.');
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let res = count_arrangements(
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CountInputs {
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cs: inputs.cs,
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assuming_first_char: Some('.'),
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in_run: inputs.in_run,
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runs: inputs.runs.clone(),
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},
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cache,
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) + count_arrangements(
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CountInputs {
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cs: inputs.cs,
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assuming_first_char: Some('#'),
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in_run: inputs.in_run,
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runs: inputs.runs.clone(),
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},
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cache,
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);
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cache.insert(inputs, res);
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return res;
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} else if first == '.' {
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if inputs.in_run {
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// the current run ended prematurely
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cache.insert(inputs, 0);
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return 0;
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} else {
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// accepted.push('.');
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return count_arrangements(
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CountInputs {
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cs: &inputs.cs[1..],
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assuming_first_char: None,
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in_run: false,
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runs: inputs.runs,
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},
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cache,
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);
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}
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} else {
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panic!("unexpected char {}", first);
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn count(cs: &str, runs: Vec<u8>, expected: usize) {
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let cs = cs.chars().collect::<Vec<_>>();
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assert_eq!(
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count_arrangements(
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CountInputs {
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cs: &cs,
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assuming_first_char: None,
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in_run: false,
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runs,
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},
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&mut HashMap::new(),
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),
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expected
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);
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}
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#[test]
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fn test1() {
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count("???.###", vec![1, 1, 3], 1);
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}
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#[test]
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fn test2() {
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count(".??..??...?##.", vec![1, 1, 3], 4);
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}
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#[test]
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fn test3() {
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count("?#?#?#?#?#?#?#?", vec![1, 3, 1, 6], 1);
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}
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#[test]
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fn test4() {
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count("????.#...#...", vec![4, 1, 1], 1);
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}
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#[test]
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fn test5() {
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count("????.######..#####", vec![1, 6, 5], 4);
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}
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#[test]
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fn test6() {
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count("?###????????", vec![3, 2, 1], 10);
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}
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fn unfold(cs: &str, mut runs: Vec<u8>, expected: usize) {
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let mut cs = cs.chars().collect::<Vec<_>>();
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unfold_line(&mut cs, &mut runs);
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assert_eq!(
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count_arrangements(
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CountInputs {
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cs: &cs,
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assuming_first_char: None,
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in_run: false,
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runs,
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},
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&mut HashMap::new()
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),
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expected
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);
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}
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#[test]
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fn unfolded() {
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unfold("???.###", vec![1, 1, 3], 1);
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unfold(".??..??...?##.", vec![1, 1, 3], 16384);
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unfold("?#?#?#?#?#?#?#?", vec![1, 3, 1, 6], 1);
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unfold("????.#...#...", vec![4, 1, 1], 16);
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unfold("????.######..#####.", vec![1, 6, 5], 2500);
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unfold("?###????????", vec![3, 2, 1], 506250);
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}
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}
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@ -12,7 +12,8 @@ mod day08;
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mod day09;
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mod day10;
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mod day11;
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mod day12;
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fn main() {
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day11::run();
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day12::run();
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}
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