day6

src/day6.rs

@@ -1,5 +1,7 @@
 type Input = ((usize, usize), Vec<Vec<u8>>);
 
+use std::collections::HashSet;
+
 use aoc_runner_derive::{aoc, aoc_generator};
 #[aoc_generator(day6)]
 fn parse(input: &str) -> Input {
@@ -98,7 +100,7 @@ fn part2(input: &Input) -> u64 {
         );
         if map[next_pos.1][next_pos.0] != 1 {
             map[next_pos.1][next_pos.0] = 1;
-            if check_loop(initial, (0, -1), &map) {
+            if check_loop(pos, dir, &map) {
                 // count += 1;
                 if !(loops.contains(&next_pos)) && next_pos != initial {
                     loops.push(next_pos);
@@ -112,12 +114,22 @@ fn part2(input: &Input) -> u64 {
     loops.len() as u64
 }
 
-fn check_loop(pos: (usize, usize), dir: (isize, isize), map: &[Vec<u8>]) -> bool {
-    let mut visited = vec![];
+static mut VISITED: [[[bool; 4]; 130]; 130] = [[[false; 4]; 130]; 130];
+static mut VISITED_VEC: Vec<(usize, usize, usize)> = vec![];
 
+fn check_loop(pos: (usize, usize), dir: (isize, isize), map: &[Vec<u8>]) -> bool {
     let h = map.len();
     let w = map[0].len();
 
+    unsafe {
+        VISITED_VEC.clear();
+        VISITED_VEC.reserve(w * h * 4);
+    }
+
+    // let mut visited = [[[false; 4]; 130]; 130];
+    // let mut visited = HashSet::with_capacity(h * w * 4);
+    // let mut visited = 0;
+
     let mut dir = dir;
     let mut pos = pos;
 
@@ -143,20 +155,37 @@ fn check_loop(pos: (usize, usize), dir: (isize, isize), map: &[Vec<u8>]) -> bool
 
             turns += 1;
         }
+        if turns == 2 {
+            break;
+        }
         pos = (
             (pos.0 as isize + dir.0) as usize,
             (pos.1 as isize + dir.1) as usize,
         );
-        if visited.contains(&(pos.0, pos.1, dir.0, dir.1)) {
-            return true;
-        } else if turns > 0 {
-            visited.push((pos.0, pos.1, dir.0, dir.1));
+        let dirnum = ((dir.1 + 1) >> 2) as usize + (dir.0 + 1) as usize;
+        unsafe {
+            if VISITED[pos.1][pos.0][dirnum] {
+                clear_visited();
+                return true;
+            } else if turns > 0 {
+                VISITED[pos.1][pos.0][dirnum] = true;
+                VISITED_VEC.push((pos.0, pos.1, dirnum));
+            }
         }
     }
 
+    unsafe {
+        clear_visited();
+    }
+
     false
 }
 
+unsafe fn clear_visited() {
+    VISITED_VEC
+        .iter()
+        .for_each(|(a, b, c)| VISITED[*b][*a][*c] = false);
+}
 #[cfg(test)]
 mod tests {
     use super::*;