2023.04

challenges/2023/04-scratchcards/README.md

@@ -0,0 +1 @@
+# [Day 4: Scratchcards](https://adventofcode.com/2023/day/4)

challenges/2023/04-scratchcards/main.py

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+import sys
+from dataclasses import dataclass
+import functools
+from typing import Callable
+
+
+@dataclass()
+class Card:
+    id: int
+    winning: set[int]
+    present: set[int]
+
+    def __init__(self, id: int):
+        self.id = id
+        self.winning = set()
+        self.present = set()
+
+    def __hash__(self) -> int:
+        return hash(self.id)
+
+    def get_winning_numbers(self) -> set[int]:
+        return self.winning & self.present
+
+    def calculate_score(self) -> int:
+        n = len(self.get_winning_numbers())
+        score = 0 if n == 0 else 2**(n-1)
+        return score
+
+    def get_prize_copies(self) -> set[int]:
+        return set(map(lambda x: self.id + x + 1, range(len(self.get_winning_numbers()))))
+
+
+def make_card_counter(all_cards: list[Card]) -> Callable[[Card], int]:
+    @functools.cache
+    def fn(c: Card) -> int:
+        acc = 1
+        won = c.get_prize_copies()
+        
+        for won_card in won:
+            acc += fn(all_cards[won_card-1])
+
+        return acc
+    return fn
+
+
+def parse(instr: str) -> list[Card]:
+    res = []
+
+    for line in instr.splitlines():
+        card_decl, numbers_sect = line.split(": ")
+        
+        card = Card(int(card_decl.lstrip("Card ")))
+
+        winning, present = numbers_sect.split("|")
+        card.winning = set([int(x) for x in winning.split(" ") if x != ""])
+        card.present = set([int(x) for x in present.split(" ") if x != ""])
+
+        res.append(card)
+    
+    return res
+
+
+def one(instr: str) -> int:
+    cards = parse(instr)
+    return sum(x.calculate_score() for x in cards)
+
+
+def two(instr: str) -> int:
+    cards = parse(instr)
+    acc = 0
+
+    count_fn = make_card_counter(cards)
+
+    for card in cards:
+        acc += count_fn(card)
+    return acc
+
+
+def _debug(*args, **kwargs):
+    kwargs["file"] = sys.stderr
+    print(*args, **kwargs)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2 or sys.argv[1] not in ["1", "2"]:
+        print("Missing day argument", file=sys.stderr)
+        sys.exit(1)
+    inp = sys.stdin.read().strip()
+    if sys.argv[1] == "1":
+        print(one(inp))
+    else:
+        print(two(inp))

challenges/2023/04-scratchcards/tests.json

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+{
+    "1": [
+        {"is": "13", "input": "Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53\nCard 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19\nCard 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1\nCard 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83\nCard 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36\nCard 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11\n"}
+    ],
+    "2": [
+        {"is": "30", "input": "Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53\nCard 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19\nCard 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1\nCard 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83\nCard 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36\nCard 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11\n"}
+    ]
+}

challenges/2023/README.md

@@ -11,5 +11,6 @@ Solutions to the [2023 Advent of Code](https://adventofcode.com/2023).
 | Day | Status | Solutions | Notes |
 |-----|--------|-----------|-------|
 | 01 - Trebuchet?! | ★ ★ | Python | I never knew detecting numbers could be so confusingly tricky |
-| 01 - Cube Conundrum | ★ ★ | Python | Pleasingly straightforwards, though seems like it would be well suited to Haskell |
-| 01 - Gear Ratios | ★ ★ | Python | First coordinate grid of the year! |
+| 02 - Cube Conundrum | ★ ★ | Python | Pleasingly straightforwards, though seems like it would be well suited to Haskell |
+| 03 - Gear Ratios | ★ ★ | Python | First coordinate grid of the year! |
+| 04 - Scratchcards | ★ ★ | Python | First flawed initial grok of the year |