feat: day09 (#12)

Author: martabal

Cargo.lock

@@ -9,6 +9,7 @@ members = [
     "crates/day06",
     "crates/day07",
     "crates/day08",
+    "crates/day09",
     "crates/helpers",
 ]
 

Cargo.toml

@@ -19,3 +19,4 @@ Ideally, the solution does not use external crates/dependencies.
 |   6   |   ✅    |   ✅    |   ✅    |   ✅    |   ✅    |   ✅    |
 |   7   |   ✅    |   ✅    |   ✅    |   ✅    |   ✅    |   ✅    |
 |   8   |   ✅    |   ✅    |   ✅    |   ✅    |   ❌    |   ❌    |
+|   9   |   ✅    |   ✅    |   ❌    |   ❌    |   ❌    |   ❌    |

README.md

@@ -0,0 +1,2 @@
+Part One solution: 323
+Part Two solution: 1077

crates/day08/.response

@@ -133,7 +133,7 @@ fn main() {
     let checker = Antenna::new(&message);
     println!("Part One solution: {:?}", checker.count_antennas(false));
     // --- Part Two ---
-    println!("Part One solution: {:?}", checker.count_antennas(true));
+    println!("Part Two solution: {:?}", checker.count_antennas(true));
 }
 
 #[cfg(test)]

crates/day08/src/main.rs

@@ -0,0 +1,2 @@
+Part One solution: 6288707484810
+Part Two solution: 6311837662089

crates/day09/.response

@@ -0,0 +1,10 @@
+[package]
+name = "day09"
+version = "0.1.0"
+edition = "2021"
+
+[lints]
+workspace = true
+
+[dependencies]
+helpers = { path = "../helpers"}

crates/day09/Cargo.toml

@@ -0,0 +1 @@
+2333133121414131402

crates/day09/example_input.txt

@@ -0,0 +1,193 @@
+use helpers::read_file;
+
+#[derive(Clone, Copy, Debug)]
+enum File {
+    Free,
+    Taken(u32),
+}
+
+struct FileSystem {
+    files: Vec<File>,
+    defragmented_files: Vec<File>,
+}
+
+impl FileSystem {
+    fn new(content: &str) -> Self {
+        let mut files: Vec<File> = Vec::new();
+        let mut id = 0;
+        for line in content.lines() {
+            for (i, c) in line.chars().enumerate() {
+                if let Some(digit) = c.to_digit(10) {
+                    if i % 2 == 0 {
+                        files.extend(
+                            std::iter::repeat(File::Taken(id)).take(digit.try_into().unwrap()),
+                        );
+                        id += 1;
+                    } else {
+                        files.extend(std::iter::repeat(File::Free).take(digit.try_into().unwrap()));
+                    }
+                }
+            }
+        }
+        let defragmented_files = files.clone();
+        Self {
+            files,
+            defragmented_files,
+        }
+    }
+
+    fn count_free_files(files: &[File], index: usize) -> usize {
+        let mut count = 0;
+        for i in index..files.len() {
+            match files.get(i) {
+                Some(File::Free) => {
+                    count += 1;
+                }
+                Some(File::Taken(_)) | None => {
+                    break;
+                }
+            }
+        }
+
+        count
+    }
+
+    fn detect_block(files: &[File], index_end: usize) -> Option<(usize, usize)> {
+        let mut current_block: Option<(u32, usize)> = None;
+
+        for i in (0..index_end).rev() {
+            match files.get(i) {
+                Some(File::Free) => {
+                    if let Some(new_block) = current_block {
+                        return Some((i + 1, new_block.1));
+                    }
+                    current_block = None;
+                }
+                Some(File::Taken(digit)) => {
+                    if current_block.is_none() {
+                        current_block = Some((*digit, 1));
+                    } else if *digit != current_block.unwrap().0 {
+                        return Some((i + 1, current_block.unwrap().1));
+                    } else {
+                        current_block = Some((*digit, current_block.unwrap().1 + 1));
+                    }
+                }
+                None => {
+                    break;
+                }
+            }
+        }
+
+        None
+    }
+
+    fn fragment_files(&mut self) {
+        for i in 0..self.defragmented_files.len() {
+            match self.defragmented_files.get(i) {
+                Some(File::Free) => {
+                    if let Some((index, _)) = self
+                        .defragmented_files
+                        .iter()
+                        .enumerate()
+                        .rfind(|&(j, file)| j > i && matches!(file, File::Taken(_)))
+                    {
+                        self.defragmented_files.swap(i, index);
+                    }
+                }
+                Some(File::Taken(_)) | None => {}
+            }
+        }
+    }
+
+    fn fragment_files_block(&mut self) {
+        let mut end_vec = self.files.len();
+        while let Some((start_index, size)) = Self::detect_block(&self.files, end_vec) {
+            let mut following_free_file = false;
+            for (index, file) in self.files.iter().enumerate() {
+                match file {
+                    File::Free => {
+                        if !following_free_file {
+                            following_free_file = true;
+                            let number_free_files = Self::count_free_files(&self.files, index);
+                            if number_free_files >= size && index < start_index {
+                                for j in 0..size {
+                                    self.files.swap(index + j, start_index + j);
+                                }
+
+                                break;
+                            }
+                        }
+                    }
+                    File::Taken(_) => following_free_file = false,
+                }
+            }
+            end_vec = start_index;
+        }
+    }
+
+    fn calculate_checksum(files: &[File]) -> u64 {
+        files
+            .iter()
+            .enumerate() // Get position (index) along with each file
+            .filter_map(|(pos, file)| {
+                if let File::Taken(id) = file {
+                    // println!("{pos} * {id} [{file:?}]");
+                    Some(pos as u64 * u64::from(*id))
+                } else {
+                    None
+                }
+            })
+            .sum()
+    }
+}
+
+fn main() {
+    let message = read_file("crates/day09/input.txt").unwrap();
+
+    // --- Part One ---
+    let mut checker = FileSystem::new(&message);
+    checker.fragment_files();
+    println!(
+        "Part One solution: {:?}",
+        FileSystem::calculate_checksum(&checker.defragmented_files)
+    );
+    // --- Part Two ---
+    checker.fragment_files_block();
+    println!(
+        "Part Two solution: {:?}",
+        FileSystem::calculate_checksum(&checker.files)
+    );
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn check_exemple() {
+        let message = read_file("example_input.txt").unwrap();
+
+        let mut checker = FileSystem::new(&message);
+        checker.fragment_files();
+        checker.fragment_files_block();
+        let response_part_1 = FileSystem::calculate_checksum(&checker.defragmented_files);
+        let response_part_2 = FileSystem::calculate_checksum(&checker.files);
+
+        assert!(response_part_1 == 1928);
+        assert!(response_part_2 == 2858);
+    }
+
+    #[test]
+    fn check_result() {
+        let message = read_file("input.txt").unwrap();
+
+        let mut checker = FileSystem::new(&message);
+        checker.fragment_files();
+        checker.fragment_files_block();
+        let response_part_1 = FileSystem::calculate_checksum(&checker.defragmented_files);
+        let response_part_2 = FileSystem::calculate_checksum(&checker.files);
+
+        assert!(response_part_1 == 6288707484810);
+        assert!(response_part_2 == 6311837662089);
+    }
+}