Day 4 try using bit comparisons to find bingo.

This is actually slower for some reason.

2021/src/day4.rs

@@ -140,10 +140,45 @@ impl FromStr for Game {
     }
 }
 
+#[derive(Default)]
+struct MarkerBoard(u32);
+
+impl MarkerBoard {
+    fn mark(&mut self, (x, y): (usize, usize)) {
+        let bit = 1 << (x + y * 5);
+        self.0 |= bit;
+    }
+
+    fn is_marked(&self, (x, y): (usize, usize)) -> bool {
+        let bit = 1 << (x + y * 5);
+        (self.0 & bit) != 0
+    }
+
+    fn is_bingo(&self) -> bool {
+        let h = 0b11111;
+        let v = 0b00001_00001_00001_00001_00001;
+        let m = self.0;
+
+        // Bingo horizontally
+        false
+            || (m & h == h)
+            || ((m >> 5 & h) == h)
+            || ((m >> 10 & h) == h)
+            || ((m >> 15 & h) == h)
+            || ((m >> 20 & h) == h)
+        // Bingo vertically
+            || ((m & v) == v)
+            || ((m >> 1 & v) == v)
+            || ((m >> 2 & v) == v)
+            || ((m >> 3 & v) == v)
+            || ((m >> 4 & v) == v)
+    }
+}
+
 #[derive(Default)]
 struct Board {
     numbers: HashMap<(usize, usize), u64>,
-    marked: HashSet<(usize, usize)>,
+    marked: MarkerBoard,
 }
 
 #[derive(Debug, Error)]
@@ -154,23 +189,13 @@ enum BoardError {
 
 impl Board {
     fn is_bingo(&self) -> bool {
-        for y in 0..5 {
-            if (0..5).all(|x| self.marked.contains(&(x, y))) {
-                return true;
-            }
-        }
-        for x in 0..5 {
-            if (0..5).all(|y| self.marked.contains(&(x, y))) {
-                return true;
-            }
-        }
-        false
+        self.marked.is_bingo()
     }
     fn sum_uncovered(&self) -> u64 {
         self.numbers
             .iter()
             .map(|((x, y), v)| {
-                if !self.marked.contains(&(*x, *y)) {
+                if !self.marked.is_marked((*x, *y)) {
                     *v
                 } else {
                     0
@@ -182,7 +207,7 @@ impl Board {
     fn mark(&mut self, num: u64) -> bool {
         for ((x, y), v) in self.numbers.iter() {
             if *v == num {
-                self.marked.insert((*x, *y));
+                self.marked.mark((*x, *y));
                 return true;
             }
         }
@@ -195,7 +220,7 @@ impl Debug for Board {
         writeln!(f)?;
         for y in 0..5 {
             for x in 0..5 {
-                if self.marked.contains(&(x, y)) {
+                if self.marked.is_marked((x, y)) {
                     let v = format!("{:3}", self.numbers[&(x, y)]);
                     write!(f, "{}", Green.bold().paint(v))?;
                 } else {

2021/src/day6.rs

@@ -88,10 +88,16 @@ fn part2(input: &str) -> Result<usize> {
         .into_iter()
         .for_each(|n| counts[n] += 1);
     for _ in 0..256 {
-        let ready = counts[0];
-        counts.rotate_left(1);
-        counts[6] += ready;
-        counts[8] = ready;
+        let mut tmp = [0; 9];
+        for (i, c) in counts.iter().enumerate() {
+            if i == 0 {
+                tmp[6] = *c;
+                tmp[8] = *c;
+            } else {
+                tmp[i - 1] += *c;
+            }
+        }
+        counts = tmp;
     }
     Ok(counts.iter().sum())
 }