add day12

Author: mirsella

2023/Cargo.toml

@@ -13,7 +13,7 @@ members = [
   "day9",
   "day10",
   "day11",
-  # "day12",
+  "day12",
   # "day13",
   # "day14",
   # "day15",

2023/day12/.gitignore

@@ -0,0 +1,19 @@
+input.txt
+flamegraph.svg
+perf.data*
+### Rust
+# Generated by Cargo
+# will have compiled files and executables
+debug/
+target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds of rustc generate these, which store debugging information
+*.pdb
+

2023/day12/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day12"
+authors = ["mirsella <mirsella@protonmail.com>"]
+version = "0.1.0"
+edition = "2021"
+

2023/day12/build.rs

@@ -0,0 +1,28 @@
+use std::fs::File;
+use std::io::{self, Read};
+use std::path::PathBuf;
+use std::{env, fs};
+
+fn replace_in_file(file_path: &PathBuf, old: &str, new: &str) -> io::Result<()> {
+    let mut contents = String::new();
+    File::open(file_path)?.read_to_string(&mut contents)?;
+    let new_contents = contents.replace(old, new);
+    if contents != new_contents {
+        println!("Updating {}", file_path.display());
+        fs::write(file_path, new_contents)?;
+    }
+    Ok(())
+}
+
+fn main() -> io::Result<()> {
+    let pkg_name = env::var("CARGO_PKG_NAME").unwrap();
+    replace_in_file(
+        &"../Cargo.toml".into(),
+        &format!("# \"{pkg_name}\""),
+        &format!("\"{pkg_name}\""),
+    )?;
+
+    replace_in_file(&"./Cargo.toml".into(), "\n[workspace]", "")?;
+
+    Ok(())
+}

2023/day12/src/main.rs

@@ -0,0 +1,83 @@
+use std::iter;
+
+fn find_all_permutations(pattern: &str, counts: impl Iterator<Item = usize>) -> usize {
+    let mut bytes = vec![b'.'];
+    bytes.extend(pattern.trim_end_matches('.').as_bytes());
+    let pattern = bytes;
+    let mut vec = vec![0; pattern.len() + 1];
+    vec[0] = 1;
+
+    for (i, _) in pattern.iter().take_while(|&&c| c != b'#').enumerate() {
+        vec[i + 1] = 1;
+    }
+
+    for count in counts {
+        let mut nvec = vec![0; pattern.len() + 1];
+        let mut chunk = 0;
+
+        for (i, &c) in pattern.iter().enumerate() {
+            match c == b'.' {
+                true => chunk = 0,
+                false => chunk += 1,
+            }
+            if c != b'#' {
+                nvec[i + 1] += nvec[i];
+            }
+            if chunk >= count && pattern[i - count] != b'#' {
+                nvec[i + 1] += vec[i - count];
+            }
+        }
+        vec = nvec;
+    }
+    vec.last().copied().unwrap()
+}
+
+fn part1(input: &str) -> usize {
+    input
+        .lines()
+        .map(|l| {
+            let (pattern, count) = l.split_once(' ').unwrap();
+            let counts = count.split(',').map(|c| c.parse().unwrap());
+            find_all_permutations(pattern, counts)
+        })
+        .sum()
+}
+fn part2(input: &str) -> usize {
+    input
+        .lines()
+        .map(|l| {
+            let (pattern, count) = l.split_once(' ').unwrap();
+            let counts: Vec<usize> = count.split(',').map(|c| c.parse().unwrap()).collect();
+            let unfolded_pattern = (0..4)
+                .map(|_| pattern.to_string() + "?")
+                .chain(iter::once(pattern.to_string()))
+                .collect::<String>();
+            let unfolded_counts = counts.iter().copied().cycle().take(5 * counts.len());
+            find_all_permutations(&unfolded_pattern, unfolded_counts)
+        })
+        .sum()
+}
+fn main() {
+    let input = include_str!("../input.txt");
+    println!("Part 1: {}", part1(input));
+    println!("Part 2: {}", part2(input));
+}
+
+#[cfg(test)]
+mod tests {
+    const INPUT: &str = "???.### 1,1,3
+.??..??...?##. 1,1,3
+?#?#?#?#?#?#?#? 1,3,1,6
+????.#...#... 4,1,1
+????.######..#####. 1,6,5
+?###???????? 3,2,1";
+
+    #[test]
+    fn part1() {
+        assert_eq!(super::part1(INPUT), 21);
+    }
+    #[test]
+    fn part2() {
+        assert_eq!(super::part2(INPUT), 525152);
+    }
+}