From e28ff1dd22d5d5857d5da28d94156c1e9046c5d1 Mon Sep 17 00:00:00 2001
From: timeshifter <timeshifter@sumatrae>
Date: Wed, 1 Jul 2026 20:49:23 +0200
Subject: [PATCH] refact: day 13

---
 day13/src/main.rs | 35 ++++++++++-------------------------
 1 file changed, 10 insertions(+), 25 deletions(-)

diff --git a/day13/src/main.rs b/day13/src/main.rs
index 2550a48..0e5bff6 100644
--- a/day13/src/main.rs
+++ b/day13/src/main.rs
@@ -73,31 +73,16 @@ fn get_valid_neighbors(
     maze: &[Vec<WallOrSpace>],
     (x, y): (usize, usize),
 ) -> impl Iterator<Item = (usize, usize)> {
-    let mut result = vec![];
-
-    if x == 0 && y == 0 {
-        result.push((x + 1, y));
-        result.push((x, y + 1));
-    } else if x == 0 && y != 0 {
-        result.push((x + 1, y));
-        result.push((x, y - 1));
-        result.push((x, y + 1));
-    } else if x != 0 && y == 0 {
-        result.push((x - 1, y));
-        result.push((x + 1, y));
-        result.push((x, y + 1));
-    } else {
-        // x != 0 && y != 0
-        result.push((x - 1, y));
-        result.push((x + 1, y));
-        result.push((x, y - 1));
-        result.push((x, y + 1));
-    }
-
-    result
-        .into_iter()
-        .filter(|(x, y)| *x < MAX_X && *y < MAX_Y)
-        .filter(|(x, y)| maze[*x][*y].is_space())
+    [
+        x.checked_sub(1).map(|x| (x, y)),
+        Some((x + 1, y)),
+        y.checked_sub(1).map(|y| (x, y)),
+        Some((x, y + 1)),
+    ]
+    .into_iter()
+    .flatten()
+    .filter(|(x, y)| *x < MAX_X && *y < MAX_Y)
+    .filter(|(x, y)| maze[*x][*y].is_space())
 }
 
 fn calculate_equation(x: usize, y: usize) -> usize {