add day9

Author: mirsella

2024/day9/.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
+

2024/day9/Cargo.toml

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+[package]
+name = "day9"
+authors = ["mirsella <[email protected]>"]
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+regex = { workspace = true }
+itertools = { workspace = true }
+pathfinding = { workspace = true }
+rayon = { workspace = true }
+indexmap = { workspace = true }

2024/day9/src/main.rs

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+fn part1(input: &str) -> usize {
+    let mut disk = input
+        .chars()
+        .fold((Vec::new(), true, 0), |(mut acc, is_file, mut id), char| {
+            let n = char.to_digit(10).unwrap();
+            if is_file {
+                (0..n).for_each(|_| acc.push(Some(id)));
+            } else {
+                (0..n).for_each(|_| acc.push(None));
+                id += 1;
+            }
+            (acc, !is_file, id)
+        })
+        .0;
+    let mut count = 0;
+    for i in 0..disk.len() {
+        if disk[i].is_none() {
+            if let Some(last_rev) = disk.iter().skip(i).rev().position(|&c| c.is_some()) {
+                let last = disk.len() - last_rev - 1;
+                disk[i] = disk[last];
+                disk[last] = None;
+            }
+        }
+        if let Some(id) = disk[i] {
+            count += id * i;
+        }
+    }
+    count
+}
+fn part2(input: &str) -> usize {
+    let mut disk = input
+        .chars()
+        .fold((Vec::new(), true, 0), |(mut acc, is_file, mut id), char| {
+            let n = char.to_digit(10).unwrap();
+            if is_file {
+                (0..n).for_each(|_| acc.push(Some(id)));
+            } else {
+                (0..n).for_each(|_| acc.push(None));
+                id += 1;
+            }
+            (acc, !is_file, id)
+        })
+        .0;
+    let mut i = disk.len() - 1;
+    loop {
+        let mut file_size = 0;
+        if let Some(id) = disk[i] {
+            while i - file_size > 0 && disk[i - file_size].is_some_and(|c| c == id) {
+                file_size += 1;
+            }
+        }
+        if file_size > 0 {
+            for j in 0..i {
+                let mut empty_size = 0;
+                while j + empty_size < i && disk[j + empty_size].is_none() {
+                    empty_size += 1;
+                }
+                if empty_size >= file_size {
+                    (0..file_size).for_each(|k| {
+                        disk[j + k] = disk[i - k];
+                        disk[i - k] = None;
+                    });
+                }
+            }
+            i -= file_size;
+        } else if i > 1 {
+            i -= 1;
+        } else {
+            break;
+        }
+    }
+    disk.iter().enumerate().fold(0, |mut acc, (i, c)| {
+        if let Some(id) = c {
+            acc += id * i;
+        }
+        acc
+    })
+}
+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 = "2333133121414131402";
+    #[test]
+    fn part1() {
+        assert_eq!(super::part1(INPUT), 1928);
+    }
+    #[test]
+    fn part2() {
+        assert_eq!(super::part2(INPUT), 2858);
+    }
+}