switched to workspaces.

This should let me make a cross-day library.

days/day01/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "day01"
+authors.workspace = true
+description.workspace = true
+version.workspace = true
+edition.workspace = true

days/day01/src/main.rs

@@ -0,0 +1,14 @@
+mod parse;
+mod part1;
+mod part2;
+
+fn main() {
+    let _input = include_str!("./input.txt");
+    let _structured_input = parse::parse(_input);
+
+    println!("Part One");
+    println!("Result: {}", part1::part1(&_structured_input));
+
+    println!("Part Two");
+    println!("Result: {}", part2::part2(&_structured_input));
+}

days/day01/src/parse.rs

@@ -0,0 +1,48 @@
+#[derive(Debug, PartialEq, Eq)]
+pub struct Elf(pub Vec<usize>);
+
+pub fn parse(input: &str) -> Vec<Elf> {
+    input
+        .trim()
+        .split("\n\n")
+        .map(|group| {
+            Elf(group
+                .split('\n')
+                .map(|line| line.parse().unwrap())
+                .collect())
+        })
+        .collect::<Vec<Elf>>()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse() {
+        let input = "1000
+2000
+3000
+
+4000
+
+5000
+6000
+
+7000
+8000
+9000
+
+10000";
+        assert_eq!(
+            parse(input),
+            vec![
+                Elf(vec![1000, 2000, 3000]),
+                Elf(vec![4000]),
+                Elf(vec![5000, 6000]),
+                Elf(vec![7000, 8000, 9000]),
+                Elf(vec![10000])
+            ]
+        );
+    }
+}

days/day01/src/part1.rs

@@ -0,0 +1,27 @@
+use crate::parse;
+
+pub fn part1(input: &[parse::Elf]) -> usize {
+    input
+        .iter()
+        .map(|elf| elf.0.iter().sum::<usize>())
+        .max()
+        .unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part1() {
+        let input = vec![
+            parse::Elf(vec![1000, 2000, 3000]),
+            parse::Elf(vec![4000]),
+            parse::Elf(vec![5000, 6000]),
+            parse::Elf(vec![7000, 8000, 9000]),
+            parse::Elf(vec![10000]),
+        ];
+
+        assert_eq!(part1(&input), 24000);
+    }
+}

days/day01/src/part2.rs

@@ -0,0 +1,27 @@
+use crate::parse;
+
+pub fn part2(input: &[parse::Elf]) -> usize {
+    let mut input = input
+        .iter()
+        .map(|elf| elf.0.iter().sum::<usize>())
+        .collect::<Vec<usize>>();
+    input.sort_unstable();
+    input[input.len() - 3..].iter().sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part2() {
+        let input = vec![
+            parse::Elf(vec![1000, 2000, 3000]),
+            parse::Elf(vec![4000]),
+            parse::Elf(vec![5000, 6000]),
+            parse::Elf(vec![7000, 8000, 9000]),
+            parse::Elf(vec![10000]),
+        ];
+        assert_eq!(part2(&input), 45000);
+    }
+}