even smaller day 7 optimization

README.md

@@ -23,15 +23,15 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 
 | Day | Part 1 | Part 2 |
 | :---: | :---: | :---:  |
-| [Day 1](./src/bin/01.rs) | `30.8µs` | `39.3µs` |
-| [Day 2](./src/bin/02.rs) | `45.3µs` | `42.2µs` |
-| [Day 3](./src/bin/03.rs) | `117.8µs` | `116.8µs` |
-| [Day 4](./src/bin/04.rs) | `48.8µs` | `50.4µs` |
-| [Day 5](./src/bin/05.rs) | `20.7µs` | `24.3µs` |
-| [Day 6](./src/bin/06.rs) | `203.0ns` | `96.0ns` |
-| [Day 7](./src/bin/07.rs) | `100.7µs` | `97.0µs` |
-
-**Total: 0.73ms**
+| [Day 1](./src/bin/01.rs) | `33.9µs` | `36.0µs` |
+| [Day 2](./src/bin/02.rs) | `41.5µs` | `40.8µs` |
+| [Day 3](./src/bin/03.rs) | `116.5µs` | `115.9µs` |
+| [Day 4](./src/bin/04.rs) | `49.4µs` | `49.7µs` |
+| [Day 5](./src/bin/05.rs) | `20.9µs` | `24.1µs` |
+| [Day 6](./src/bin/06.rs) | `202.0ns` | `100.0ns` |
+| [Day 7](./src/bin/07.rs) | `93.6µs` | `92.6µs` |
+
+**Total: 0.72ms**
 <!--- benchmarking table --->
 
 ---

src/bin/07.rs

@@ -65,8 +65,7 @@ enum HandType {
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Default)]
 struct Hand {
     hand_type: HandType,
-    cards: [Card; 5],
-    cards_ordering: [usize; 5],
+    cards_ordering: [u8; 5],
     joker: Option<Card>,
 }
 
@@ -79,16 +78,17 @@ impl Hand {
             joker,
             ..Default::default()
         };
+        let mut cards: [Card; 5] = Default::default();
         for (i, card) in s.chars().map(Card::try_from).enumerate() {
             let card = card?;
-            hand.cards[i] = card;
+            cards[i] = card;
             hand.cards_ordering[i] = match (joker, card) {
                 (Some(j), c) if j == c => 0,
-                (Some(_), c) => c.ordinal() as usize + 1,
-                (None, c) => c.ordinal() as usize,
+                (Some(_), c) => c.ordinal() as u8 + 1,
+                (None, c) => c.ordinal() as u8,
             }
         }
-        hand.hand_type = hand_type(hand.cards, joker);
+        hand.hand_type = hand_type(cards, joker);
         Ok(hand)
     }
 }