From 49e11349f574acad0ca08e809cc5a78fb3354081 Mon Sep 17 00:00:00 2001
From: Jan-Bulthuis <git@bulthuis.dev>
Date: Mon, 9 Dec 2024 13:06:37 +0100
Subject: [PATCH] Removed hashset from day8

---
 aoc_2024/src/day8.rs | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/aoc_2024/src/day8.rs b/aoc_2024/src/day8.rs
index 030c313..fe90976 100644
--- a/aoc_2024/src/day8.rs
+++ b/aoc_2024/src/day8.rs
@@ -1,4 +1,4 @@
-use hashbrown::{HashMap, HashSet};
+use hashbrown::HashMap;
 
 use aoc_runner_derive::{aoc, aoc_generator};
 
@@ -25,7 +25,8 @@ fn parse(input: &str) -> Input {
 
 #[aoc(day8, part1)]
 fn part1(input: &Input) -> usize {
-    let mut set = HashSet::new();
+    let mut set = [[false; 64]; 64];
+    let mut sum = 0;
     input.1.iter().for_each(|vec| {
         for l in 0..vec.len() {
             for r in l + 1..vec.len() {
@@ -33,11 +34,23 @@ 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.insert(c1);
+                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 c2.0 >= 0 && c2.0 < input.0 .0 && c2.1 >= 0 && c2.1 < input.0 .1 {
-                    set.insert(c2);
+                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;
                 }
             }
         }
@@ -47,7 +60,8 @@ fn part1(input: &Input) -> usize {
 
 #[aoc(day8, part2)]
 fn part2(input: &Input) -> usize {
-    let mut set = HashSet::with_capacity(input.1.len() * input.1.len());
+    let mut set = [[false; 64]; 64];
+    let mut sum = 0;
     input.1.iter().for_each(|vec| {
         for l in 0..vec.len() {
             for r in l + 1..vec.len() {
@@ -60,7 +74,10 @@ 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 {
-                        set.insert(c);
+                        if !set[c.1 as usize][c.0 as usize] {
+                            set[c.1 as usize][c.0 as usize] = true;
+                            sum += 1;
+                        };
                     } else {
                         break;
                     }
@@ -70,7 +87,10 @@ 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 {
-                        set.insert(c);
+                        if !set[c.1 as usize][c.0 as usize] {
+                            set[c.1 as usize][c.0 as usize] = true;
+                            sum += 1;
+                        };
                     } else {
                         break;
                     }
@@ -78,7 +98,7 @@ fn part2(input: &Input) -> usize {
             }
         }
     });
-    set.len()
+    sum
 }
 
 #[cfg(test)]