day 12

Cargo.lock

@@ -143,6 +143,14 @@ dependencies = [
  "rayon",
 ]
 
+[[package]]
+name = "day-12"
+version = "0.0.0"
+dependencies = [
+ "indoc",
+ "nom",
+]
+
 [[package]]
 name = "deprecate-until"
 version = "0.1.1"

Cargo.toml

@@ -1,16 +1,10 @@
 [workspace]
 resolver = "2"
 members = [
-    "day-01",
-    "day-02",
-    "day-03",
-    "day-05",
-    "day-06",
-    "day-07",
-    "day-08",
-    "day-09",
-    "day-10",
-    "day-11"
+    "day-*"
+]
+exclude = [
+    "day-04"
 ]
 
 [workspace.dependencies]

day-12/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "day-12"
+version = "0.0.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+nom.workspace = true
+
+[dev-dependencies]
+indoc.workspace = true

day-12/src/bin/part1.rs

@@ -0,0 +1,116 @@
+use nom::{branch::alt, character::complete, combinator::value, multi::many1};
+
+fn main() {
+    println!("{}", part1(include_str!("./input.txt")));
+}
+
+fn part1(input: &str) -> u32 {
+    input.lines().map(process_line).sum()
+}
+
+fn process_line(line: &str) -> u32 {
+    let (springs_str, group_size_str) = line.split_once(' ').expect("Invalid input");
+
+    let group_size = group_size_str
+        .split(',')
+        .map(|s| s.parse::<usize>().expect("invalid char as number"))
+        .collect::<Vec<_>>();
+
+    let springs = many1(alt((
+        value(
+            SpringStatus::Operational,
+            complete::char::<&str, nom::error::Error<&str>>('.'),
+        ),
+        value(
+            SpringStatus::Damaged,
+            complete::char::<&str, nom::error::Error<&str>>('#'),
+        ),
+        value(
+            SpringStatus::Unknown,
+            complete::char::<&str, nom::error::Error<&str>>('?'),
+        ),
+    )))(springs_str)
+    .expect("Invalid input")
+    .1;
+
+    let spring_amount = springs.len();
+    let groups_amount = group_size.len();
+    let mut dp = vec![vec![vec![0; spring_amount + 1]; groups_amount + 1]; spring_amount + 1];
+
+    dp[spring_amount][groups_amount][0] = 1;
+    dp[spring_amount][groups_amount - 1][group_size[groups_amount - 1]] = 1;
+
+    for pos in (0..spring_amount).rev() {
+        for (group, &max_count) in group_size.iter().enumerate() {
+            // try iteratively all possible counts for the current group
+            for count in 0..=max_count {
+                // try both operational and damaged for each position
+                for &c in &[SpringStatus::Operational, SpringStatus::Damaged] {
+                    // only proceed if the spring is of the chosen type or unknown
+                    if springs[pos] == c || springs[pos] == SpringStatus::Unknown {
+                        if c == SpringStatus::Operational && count == 0 {
+                            // if operational and count is 0, then add the value from the next position because
+                            // there is no new combination
+                            dp[pos][group][count] += dp[pos + 1][group][0];
+                        } else if c == SpringStatus::Operational && group_size[group] == count {
+                            // if operational and count is equal to the group size, then add the value from the
+                            // next position and next group
+                            dp[pos][group][count] += dp[pos + 1][group + 1][0];
+                        } else if c == SpringStatus::Damaged {
+                            // if damaged, then add the value from the next position and next count
+                            dp[pos][group][count] += dp[pos + 1][group][count + 1];
+                        }
+                    }
+                }
+            }
+        }
+        if matches!(
+            springs[pos],
+            SpringStatus::Operational | SpringStatus::Unknown
+        ) {
+            dp[pos][groups_amount][0] += dp[pos + 1][groups_amount][0];
+        }
+    }
+
+    dp[0][0][0]
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum SpringStatus {
+    Operational,
+    Damaged,
+    Unknown,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn test_part1() {
+        assert_eq!(
+            part1(indoc!(
+                "
+                ???.### 1,1,3
+                .??..??...?##. 1,1,3
+                ?#?#?#?#?#?#?#? 1,3,1,6
+                ????.#...#... 4,1,1
+                ????.######..#####. 1,6,5
+                ?###???????? 3,2,1
+                "
+            )),
+            21
+        );
+    }
+
+    #[test]
+    fn test_process_line_part1() {
+        assert_eq!(process_line("???.### 1,1,3"), 1);
+        assert_eq!(process_line(".??..??...?##. 1,1,3"), 4);
+        assert_eq!(process_line("?#?#?#?#?#?#?#? 1,3,1,6"), 1);
+        assert_eq!(process_line("????.#...#... 4,1,1"), 1);
+        assert_eq!(process_line("????.######..#####. 1,6,5"), 4);
+        assert_eq!(process_line("?###???????? 3,2,1"), 10);
+    }
+}

day-12/src/bin/part2.rs

@@ -0,0 +1,135 @@
+use std::vec;
+
+use nom::{branch::alt, character::complete, combinator::value, multi::many1};
+
+fn main() {
+    println!("{}", part2(include_str!("./input.txt")));
+}
+
+fn part2(input: &str) -> u64 {
+    input.lines().map(process_line).sum()
+}
+
+fn process_line(line: &str) -> u64 {
+    let (springs_str, group_size_str) = line.split_once(' ').expect("Invalid input");
+
+    let group_size = group_size_str
+        .split(',')
+        .map(|s| s.parse::<usize>().expect("invalid char as number"))
+        .collect::<Vec<_>>()
+        .repeat(5);
+
+    let springs = many1(alt((
+        value(
+            SpringStatus::Operational,
+            complete::char::<&str, nom::error::Error<&str>>('.'),
+        ),
+        value(
+            SpringStatus::Damaged,
+            complete::char::<&str, nom::error::Error<&str>>('#'),
+        ),
+        value(
+            SpringStatus::Unknown,
+            complete::char::<&str, nom::error::Error<&str>>('?'),
+        ),
+    )))(springs_str)
+    .expect("Invalid input")
+    .1;
+
+    let springs = vec![
+        springs.clone(),
+        vec![SpringStatus::Unknown],
+        springs.clone(),
+        vec![SpringStatus::Unknown],
+        springs.clone(),
+        vec![SpringStatus::Unknown],
+        springs.clone(),
+        vec![SpringStatus::Unknown],
+        springs,
+    ]
+    .into_iter()
+    .flatten()
+    .collect::<Vec<_>>();
+
+    let spring_amount = springs.len();
+    let groups_amount = group_size.len();
+
+    let mut dp = vec![vec![vec![0; spring_amount + 1]; groups_amount + 1]; spring_amount + 1];
+
+    dp[spring_amount][groups_amount][0] = 1;
+    dp[spring_amount][groups_amount - 1][group_size[groups_amount - 1]] = 1;
+
+    for pos in (0..spring_amount).rev() {
+        for (group, &max_count) in group_size.iter().enumerate() {
+            // try iteratively all possible counts for the current group
+            for count in 0..=max_count {
+                // try both operational and damaged for each position
+                for &c in &[SpringStatus::Operational, SpringStatus::Damaged] {
+                    // only proceed if the spring is of the chosen type or unknown
+                    if springs[pos] == c || springs[pos] == SpringStatus::Unknown {
+                        if c == SpringStatus::Operational && count == 0 {
+                            // if operational and count is 0, then add the value from the next position because
+                            // there is no new combination
+                            dp[pos][group][count] += dp[pos + 1][group][0];
+                        } else if c == SpringStatus::Operational && group_size[group] == count {
+                            // if operational and count is equal to the group size, then add the value from the
+                            // next position and next group
+                            dp[pos][group][count] += dp[pos + 1][group + 1][0];
+                        } else if c == SpringStatus::Damaged {
+                            // if damaged, then add the value from the next position and next count
+                            dp[pos][group][count] += dp[pos + 1][group][count + 1];
+                        }
+                    }
+                }
+            }
+        }
+        if matches!(
+            springs[pos],
+            SpringStatus::Operational | SpringStatus::Unknown
+        ) {
+            dp[pos][groups_amount][0] += dp[pos + 1][groups_amount][0];
+        }
+    }
+
+    dp[0][0][0]
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum SpringStatus {
+    Operational,
+    Damaged,
+    Unknown,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+
+    #[test]
+    fn test_part2() {
+        assert_eq!(
+            part2(indoc!(
+                "
+                ???.### 1,1,3
+                .??..??...?##. 1,1,3
+                ?#?#?#?#?#?#?#? 1,3,1,6
+                ????.#...#... 4,1,1
+                ????.######..#####. 1,6,5
+                ?###???????? 3,2,1
+                "
+            )),
+            525152
+        );
+    }
+
+    #[test]
+    fn test_process_line_part2() {
+        assert_eq!(process_line("???.### 1,1,3"), 1);
+        assert_eq!(process_line(".??..??...?##. 1,1,3"), 16384);
+        assert_eq!(process_line("?#?#?#?#?#?#?#? 1,3,1,6"), 1);
+        assert_eq!(process_line("????.#...#... 4,1,1"), 16);
+        assert_eq!(process_line("????.######..#####. 1,6,5"), 2500);
+        assert_eq!(process_line("?###???????? 3,2,1"), 506250);
+    }
+}