2025 09.1

Author: Lexicality

data

@@ -0,0 +1,44 @@
+// Copyright (c) 2025 Lexi Robinson
+//
+// Licensed under the EUPL, Version 1.2
+//
+// You may not use this work except in compliance with the Licence.
+// You should have received a copy of the Licence along with this work. If not, see:
+// <https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12>.
+// See the Licence for the specific language governing permissions and limitations under the Licence.
+
+use itertools::Itertools;
+
+use crate::{AoCError, BigCoord2D, Coordinate};
+
+pub fn part_1(data: crate::DataIn) -> crate::AoCResult<String> {
+    let coords: Vec<BigCoord2D> = data.map(|line| line.parse()).try_collect()?;
+
+    let ret = coords
+        .into_iter()
+        .array_combinations()
+        .map(|[a, b]| {
+            let min = a.get_min(&b);
+            let max = a.get_max(&b);
+            ((1 + max.x - min.x) * (1 + max.y - min.y), a, b)
+        })
+        .map(|(dist, a, b)| {
+            log::debug!("Square of area {dist} between {a} and {b}");
+            dist
+        })
+        .sorted_unstable()
+        .next_back()
+        .ok_or(AoCError::new("Not enough coords??"))?;
+
+    Ok(ret.to_string())
+}
+
+inventory::submit!(crate::AoCDay {
+    year: "2025",
+    day: "9",
+    part_1: crate::AoCPart {
+        main: part_1,
+        example: part_1
+    },
+    part_2: None
+});

src/aoc/y2025/day09.rs

@@ -14,3 +14,4 @@ pub mod day05;
 pub mod day06;
 pub mod day07;
 pub mod day08;
+pub mod day09;