From 6f86208041514566e26583f0b31b92058f711e57 Mon Sep 17 00:00:00 2001
From: Daniel Flanagan <daniel@lyte.dev>
Date: Mon, 9 Dec 2024 09:38:47 -0600
Subject: [PATCH] Day 9 part 1 done

---
 2024/rust/src/day9.rs     | 58 +++++++++++++++++++++++++++++++++++++++
 2024/rust/src/template.rs | 18 ++++++++++--
 2 files changed, 73 insertions(+), 3 deletions(-)
 create mode 100644 2024/rust/src/day9.rs

diff --git a/2024/rust/src/day9.rs b/2024/rust/src/day9.rs
new file mode 100644
index 0000000..511ac86
--- /dev/null
+++ b/2024/rust/src/day9.rs
@@ -0,0 +1,58 @@
+mod prelude;
+pub use crate::prelude::*;
+
+fn main() {
+    let input = day_input(9);
+    show_answers(part1(&input), part2(&input));
+}
+
+fn part1(input: &str) -> usize {
+    let mut blocks: Vec<Option<usize>> = vec![];
+    let mut free_blocks: usize = 0;
+    for (i, len) in input.trim().bytes().map(|len| len - b'0').enumerate() {
+        // every other iteration is "free space"
+        let file_id = if i % 2 == 0 {
+            Some((i / 2) as usize)
+        } else {
+            free_blocks += len as usize;
+            None
+        };
+        for _ in 0..len {
+            blocks.push(file_id);
+        }
+    }
+    println!("{blocks:?}");
+    let mut right = blocks.len() - 1;
+    for left in 0..(right.clone() - free_blocks + 1) {
+        if blocks[left].is_some() {
+            continue;
+        }
+        while blocks[right].is_none() {
+            right -= 1;
+        }
+        (blocks[left], blocks[right]) = (blocks[right], blocks[left]);
+    }
+    println!("{blocks:?}");
+
+    blocks
+        .iter()
+        .enumerate()
+        .map(|(i, b)| i * b.unwrap_or_default())
+        .sum()
+}
+
+fn part2(input: &str) -> usize {
+    1
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let input = r#"2333133121414131402"#;
+        assert_eq!(part1(input), 1928);
+        assert_eq!(part2(input), 1);
+    }
+}
diff --git a/2024/rust/src/template.rs b/2024/rust/src/template.rs
index 1118127..2505311 100644
--- a/2024/rust/src/template.rs
+++ b/2024/rust/src/template.rs
@@ -2,8 +2,16 @@ mod prelude;
 pub use crate::prelude::*;
 
 fn main() {
-    let _input = day_input(0);
-    show_answers(0, 0);
+    let input = day_input(DAY);
+    show_answers(part1(&input), part2(&input));
+}
+
+fn part1(input: &str) -> i64 {
+    0
+}
+
+fn part2(input: &str) -> i64 {
+    0
 }
 
 #[cfg(test)]
@@ -11,5 +19,9 @@ mod tests {
     use super::*;
 
     #[test]
-    fn test() {}
+    fn test() {
+        let input = r#""#;
+        assert_eq!(part1(input), 1);
+        assert_eq!(part2(input), 0);
+    }
 }