Day 12 - Part 1

Signed-off-by: Anthony Oteri <anthony.oteri@gmail.com>

day-12/src/bin/part1.rs

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+use day_12::part1::process;
+use miette::Context;
+
+#[cfg(feature = "dhat-heap")]
+#[global_allocator]
+static ALLOC: dhat::Alloc = dhat::Alloc;
+
+#[tracing::instrument]
+fn main() -> miette::Result<()> {
+    #[cfg(feature = "dhat-heap")]
+    let _profiler = dhat::Profiler::new_heap();
+
+    #[cfg(not(feature = "dhat-heap"))]
+    tracing_subscriber::fmt::init();
+
+    let file = include_str!("../../input.txt");
+    let result = process(file).context("process part 1")?;
+
+    println!("{}", result);
+    Ok(())
+}

day-12/src/bin/part2.rs

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+use day_12::part2::process;
+use miette::Context;
+
+#[cfg(feature = "dhat-heap")]
+#[global_allocator]
+static ALLOC: dhat::Alloc = dhat::Alloc;
+
+#[tracing::instrument]
+fn main() -> miette::Result<()> {
+    #[cfg(feature = "dhat-heap")]
+    let _profiler = dhat::Profiler::new_heap();
+
+    #[cfg(not(feature = "dhat-heap"))]
+    tracing_subscriber::fmt::init();
+
+    let file = include_str!("../../input.txt");
+    let result = process(file).context("process part 1")?;
+
+    println!("{}", result);
+    Ok(())
+}

day-12/src/error.rs

@@ -0,0 +1,9 @@
+use miette::Diagnostic;
+use thiserror::Error;
+
+#[derive(Error, Diagnostic, Debug)]
+pub enum AocError {
+    #[error(transparent)]
+    #[diagnostic(code(aoc::io_error))]
+    IoError(#[from] std::io::Error),
+}

day-12/src/lib.rs

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+pub mod error;
+
+pub mod part1;
+pub mod part2;

day-12/src/part1.rs

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+use nom::{
+    branch::alt,
+    bytes::complete::{tag, take_until},
+    character::complete::{self, line_ending, space1},
+    combinator::eof,
+    multi::{many1, separated_list1},
+    sequence::{self, terminated},
+    IResult,
+};
+
+use crate::error::AocError;
+
+fn parse_input(input: &str) -> IResult<&str, &str> {
+    terminated(take_until(" "), space1)(input)
+}
+
+fn parse_limits(input: &str) -> IResult<&str, Vec<usize>> {
+    let (input, limits) = separated_list1(tag(","), complete::u32)(input)?;
+    Ok((input, limits.into_iter().map(|n| n as usize).collect()))
+}
+
+fn parser(input: &str) -> IResult<&str, Vec<(&str, Vec<usize>)>> {
+    many1(terminated(
+        sequence::tuple((parse_input, parse_limits)),
+        alt((line_ending, eof)),
+    ))(input)
+}
+
+pub fn gen_permutations(s: &mut String, index: usize) -> Vec<String> {
+    if index == s.len() {
+        return vec![s.clone()];
+    }
+
+    let mut permutations = Vec::new();
+
+    if s.chars().nth(index) == Some('?') {
+        s.replace_range(index..=index, ".");
+        permutations.extend(gen_permutations(s, index + 1));
+
+        s.replace_range(index..=index, "#");
+        permutations.extend(gen_permutations(s, index + 1));
+
+        s.replace_range(index..=index, "?");
+    } else {
+        permutations.extend(gen_permutations(s, index + 1));
+    }
+
+    permutations
+}
+
+fn make_regex(limits: Vec<usize>) -> String {
+    let mut r = String::from(r"^\.*");
+
+    let middle: String = limits
+        .iter()
+        .map(|n| {
+            let mut s = String::from(r"#{");
+            s.push_str(&format!("{}", n));
+            s.push('}');
+            s
+        })
+        .collect::<Vec<String>>()
+        .join(r"\.+");
+
+    r.push_str(&middle);
+    r.push_str(r"\.*$");
+
+    r
+}
+
+#[tracing::instrument]
+pub fn process(input: &str) -> miette::Result<usize, AocError> {
+    let (_, parsed) = parser(input).unwrap();
+
+    Ok(parsed
+        .into_iter()
+        .map(|(s, limits)| {
+            let mut s = String::from(s);
+            let re = regex::Regex::new(&make_regex(limits)).unwrap();
+
+            let length = gen_permutations(&mut s, 0)
+                .iter()
+                .filter(|s| re.is_match(s))
+                .count();
+
+            Ok(length)
+        })
+        .collect::<Result<Vec<usize>, AocError>>()?
+        .iter()
+        .sum::<usize>())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rstest::rstest;
+
+    #[test_log::test]
+    fn test_parser() {
+        let input = "???.### 1,1,3
+.??..??...?##. 1,1,3";
+        let result = parser(input);
+        assert!(result.is_ok());
+
+        let (rest, result) = result.unwrap();
+        assert_eq!(rest, "");
+        assert_eq!(result.len(), 2);
+        assert_eq!(result[0].0, "???.###");
+        assert_eq!(result[0].1, vec![1, 1, 3]);
+        assert_eq!(result[1].0, ".??..??...?##.");
+        assert_eq!(result[1].1, vec![1, 1, 3]);
+    }
+
+    #[test_log::test(rstest)]
+    #[case("???.### 1,1,3", 1)]
+    #[case(".??..??...?##. 1,1,3", 4)]
+    fn test_length(#[case] input: &str, #[case] expected: usize) {
+        let mut input = String::from(input);
+
+        let re = regex::Regex::new(r"^\.*#{1}\.+#{1}\.+#{3}\.*\s").unwrap();
+
+        let length = gen_permutations(&mut input, 0)
+            .iter()
+            .filter(|s| re.is_match(s))
+            .count();
+
+        assert_eq!(length, expected);
+    }
+
+    #[test_log::test]
+    fn test_make_regex() {
+        let limits = vec![1, 2, 3, 4];
+        let regex = make_regex(limits);
+        assert_eq!(regex, r"^\.*#{1}\.+#{2}\.+#{3}\.+#{4}\.*$");
+    }
+
+    #[test_log::test(rstest)]
+    #[case(("???.###", vec![1,1,3]), 1)]
+    #[case((".??..??...?##.", vec![1,1,3]), 4)]
+    #[case(("?###????????", vec![3,2,1]), 10)]
+    fn test_regex(#[case] params: (&str, Vec<usize>), #[case] expected: usize) {
+        let mut input = String::from(params.0);
+        let limits = params.1;
+
+        let re = regex::Regex::new(&make_regex(limits)).unwrap();
+
+        let length = gen_permutations(&mut input, 0)
+            .iter()
+            .filter(|s| re.is_match(s))
+            .count();
+
+        assert_eq!(length, expected);
+    }
+
+    #[test_log::test]
+    fn test_process() -> miette::Result<()> {
+        let input = include_str!("../test-input.txt");
+        assert_eq!(21, process(input)?);
+        Ok(())
+    }
+}

day-12/src/part2.rs

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+use crate::error::AocError;
+
+#[tracing::instrument]
+pub fn process(input: &str) -> miette::Result<u64, AocError> {
+    Ok(0)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test_log::test]
+    fn test_process() -> miette::Result<()> {
+        let input = include_str!("../test-input.txt");
+        assert_eq!(0, process(input)?);
+        Ok(())
+    }
+}