chore: y2025::day_09::part_1

Author: clechasseur

aoclp/src/positioning/pt.rs

@@ -177,6 +177,15 @@ where
     (a.x - b.x).abs() + (a.y - b.y).abs()
 }
 
+/// Returns the size of the rectangle formed between two points in 2D space,
+/// as if the points were the rectangle's top-left and bottom-right corners.
+pub fn rectangular_area<T>(a: Pt<T>, b: Pt<T>) -> T
+where
+    T: Signed,
+{
+    ((a.x - b.x).abs() + T::one()) * ((a.y - b.y).abs() + T::one())
+}
+
 /// Given a two-dimensional matrix of elements, returns a map of
 /// [`Pt`] associated with the element at that position in the matrix.
 pub fn matrix_to_map<T, M, R, PT>(matrix: M) -> HashMap<Pt<PT>, T>

aoclp_solutions/src/lib.rs

@@ -11,5 +11,5 @@ pub mod y2025;
 build_solvers! {
     { 2017, [01, 02, 03, 04, 05, 06, 07, 08, 09, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25] },
     { 2024, [01, 02, 03, 04, 05, 06, 07, 08, 09, 10] },
-    { 2025, [01, 02, 03, 04, 05, 06, 07, 08] }
+    { 2025, [01, 02, 03, 04, 05, 06, 07, 08, 09] }
 }

aoclp_solutions/src/y2025/day_09.rs

@@ -0,0 +1,20 @@
+use aoclp::positioning::pt::{rectangular_area, Pt};
+use aoclp::solvers_impl::input::safe_get_input_as_many;
+use itertools::Itertools;
+
+pub fn part_1() -> i64 {
+    input()
+        .into_iter()
+        .array_combinations()
+        .map(|[a, b]| rectangular_area(a, b))
+        .max()
+        .unwrap()
+}
+
+pub fn part_2() -> usize {
+    0
+}
+
+fn input() -> Vec<Pt> {
+    safe_get_input_as_many(2025, 9)
+}

aoclp_solutions/src/y2025/mod.rs

@@ -6,3 +6,4 @@ pub mod day_05;
 pub mod day_06;
 pub mod day_07;
 pub mod day_08;
+pub mod day_09;