aoc_2024/src/day8.rs

@@ -1,4 +1,4 @@
-use hashbrown::HashMap;
+use hashbrown::{HashMap, HashSet};
 
 use aoc_runner_derive::{aoc, aoc_generator};
 
@@ -25,8 +25,7 @@ fn parse(input: &str) -> Input {
 
 #[aoc(day8, part1)]
 fn part1(input: &Input) -> usize {
-    let mut set = [[false; 64]; 64];
-    let mut sum = 0;
+    let mut set = HashSet::new();
     input.1.iter().for_each(|vec| {
         for l in 0..vec.len() {
             for r in l + 1..vec.len() {
@@ -34,34 +33,21 @@ fn part1(input: &Input) -> usize {
                 let a2 = vec[r];
                 let c1 = (2 * a1.0 - a2.0, 2 * a1.1 - a2.1);
                 let c2 = (2 * a2.0 - a1.0, 2 * a2.1 - a1.1);
-                if c1.0 >= 0
-                    && c1.0 < input.0 .0
-                    && c1.1 >= 0
-                    && c1.1 < input.0 .1
-                    && !set[c1.1 as usize][c1.0 as usize]
-                {
-                    set[c1.1 as usize][c1.0 as usize] = true;
-                    sum += 1;
+                if c1.0 >= 0 && c1.0 < input.0 .0 && c1.1 >= 0 && c1.1 < input.0 .1 {
+                    set.insert(c1);
                 }
-                if c2.0 >= 0
-                    && c2.0 < input.0 .0
-                    && c2.1 >= 0
-                    && c2.1 < input.0 .1
-                    && !set[c2.1 as usize][c2.0 as usize]
-                {
-                    set[c2.1 as usize][c2.0 as usize] = true;
-                    sum += 1;
+                if c2.0 >= 0 && c2.0 < input.0 .0 && c2.1 >= 0 && c2.1 < input.0 .1 {
+                    set.insert(c2);
                 }
             }
         }
     });
-    sum
+    set.len()
 }
 
 #[aoc(day8, part2)]
 fn part2(input: &Input) -> usize {
-    let mut set = [[false; 64]; 64];
-    let mut sum = 0;
+    let mut set = HashSet::with_capacity(input.1.len() * input.1.len());
     input.1.iter().for_each(|vec| {
         for l in 0..vec.len() {
             for r in l + 1..vec.len() {
@@ -74,10 +60,7 @@ fn part2(input: &Input) -> usize {
                     let c = (s.0 + d * v.0, s.1 + d * v.1);
                     d += 1;
                     if c.0 >= 0 && c.0 < input.0 .0 && c.1 >= 0 && c.1 < input.0 .1 {
-                        if !set[c.1 as usize][c.0 as usize] {
-                            set[c.1 as usize][c.0 as usize] = true;
-                            sum += 1;
-                        };
+                        set.insert(c);
                     } else {
                         break;
                     }
@@ -87,10 +70,7 @@ fn part2(input: &Input) -> usize {
                     let c = (s.0 + d * v.0, s.1 + d * v.1);
                     d -= 1;
                     if c.0 >= 0 && c.0 < input.0 .0 && c.1 >= 0 && c.1 < input.0 .1 {
-                        if !set[c.1 as usize][c.0 as usize] {
-                            set[c.1 as usize][c.0 as usize] = true;
-                            sum += 1;
-                        };
+                        set.insert(c);
                     } else {
                         break;
                     }
@@ -98,7 +78,7 @@ fn part2(input: &Input) -> usize {
             }
         }
     });
-    sum
+    set.len()
 }
 
 #[cfg(test)]
@@ -113,10 +93,7 @@ mod tests {
             )),
             14
         );
-        assert_eq!(
-            part1(&parse(include_str!("../input/2024/day8.txt").trim_end())),
-            273
-        );
+        assert_eq!(part1(&parse(include_str!("../input/2024/day8.txt"))), 273);
     }
 
     #[test]
@@ -127,9 +104,6 @@ mod tests {
             )),
             34
         );
-        assert_eq!(
-            part2(&parse(include_str!("../input/2024/day8.txt").trim_end())),
-            1017
-        );
+        assert_eq!(part2(&parse(include_str!("../input/2024/day8.txt"))), 1017);
     }
 }