Solve 2024 day 1 part 1

jeffs · Dec 1, 2024 · 6edf60e · 6edf60e
1 parent 6e28ddb
commit 6edf60e
Showing 7 changed files with 1,064 additions and 0 deletions.
diff --git a/2024/Cargo.lock b/2024/Cargo.lock
diff --git a/2024/Cargo.toml b/2024/Cargo.toml
@@ -0,0 +1,3 @@
+[workspace]
+members = ["day1"]
+resolver = "2"
diff --git a/2024/day1/Cargo.toml b/2024/day1/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "day1"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/2024/day1/src/lib.rs b/2024/day1/src/lib.rs
@@ -0,0 +1 @@
+pub mod part1;
diff --git a/2024/day1/src/main.rs b/2024/day1/src/main.rs
@@ -0,0 +1,6 @@
+use day1::part1;
+
+fn main() {
+    let s = include_str!("part1/input");
+    println!("{}", part1::solve(&s).unwrap());
+}
diff --git a/2024/day1/src/part1.rs b/2024/day1/src/part1.rs
@@ -0,0 +1,41 @@
+#[derive(Debug)]
+pub enum Error {
+    BadLine,
+}
+
+type Result<T> = std::result::Result<T, Error>;
+
+pub fn distance(xs: impl Into<Vec<u32>>, ys: impl Into<Vec<u32>>) -> u32 {
+    let (mut xs, mut ys) = (xs.into(), ys.into());
+    debug_assert_eq!(xs.len(), ys.len());
+    xs.sort();
+    ys.sort();
+    xs.iter().zip(ys.iter()).map(|(x, y)| x.abs_diff(*y)).sum()
+}
+
+pub fn solve(input: &str) -> Result<u32> {
+    let mut xs = Vec::new();
+    let mut ys = Vec::new();
+    for line in input.lines() {
+        let mut parts = line.split_ascii_whitespace();
+        let (Some(x), Some(y), None) = (parts.next(), parts.next(), parts.next()) else {
+            return Err(Error::BadLine);
+        };
+        let (Ok(x), Ok(y)) = (x.parse::<u32>(), y.parse::<u32>()) else {
+            return Err(Error::BadLine);
+        };
+        xs.push(x);
+        ys.push(y);
+    }
+    Ok(distance(xs, ys))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_distance() {
+        assert_eq!(distance([3, 4, 2, 1, 3, 3], [4, 3, 5, 3, 9, 3]), 11);
+    }
+}