From d4e7bca3931a8e9246639bd5ae2d4ede1fa8e0b1 Mon Sep 17 00:00:00 2001
From: aaron <aaron@duckpond.ch>
Date: Mon, 4 Dec 2023 21:15:27 +0100
Subject: [PATCH] solution to part a using list comprehensions

---
 4/scratchcards.py | 57 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 4/scratchcards.py

diff --git a/4/scratchcards.py b/4/scratchcards.py
new file mode 100644
index 0000000..a1555be
--- /dev/null
+++ b/4/scratchcards.py
@@ -0,0 +1,57 @@
+from aocd.models import Puzzle
+from aocd import submit
+from dataclasses import dataclass
+import math
+import re
+
+
+def get_winning_numbers(input_data: str) -> list:
+    """
+    Parse input_data, extract all cards and turn them into sets.
+    Return the intersection between numbers and winning numbers.
+    """
+
+    # separate cards into a list of strings and remove excess whitespace
+    pairs = [ " ".join(card.split()) for card in input_data.split("\n") ]
+    # extract a set of winning numbers
+    winners = [ set(pair.split(":")[1].split("|")[0].strip().split(" ")) for pair in pairs ]
+    # extract a set of scratch numbers
+    numbers = [ set(pair.split(":")[1].split("|")[1].strip().split(" ")) for pair in pairs ]
+    # calculate set intersection between numbers and winning numbers
+    intersections = [ numbers[i].intersection(winners[i]) for i in range(len(numbers)) ]
+
+    return intersections
+
+def calculate_score(winning_numbers:list) -> list:
+    """
+    Calculate the score for each number
+    - 0 points for no match
+    - 1 point for 1 match
+    - double the points for each successive match
+    """
+    scores = []
+    for i, win in enumerate(winning_numbers):
+        if len(win) == 0:
+            scores.append(0)
+        if len(win) == 1:
+            scores.append(1)
+        if len(win) > 1:
+            scores.append(2**(len(win) - 1))
+    return scores
+
+
+if __name__ == "__main__":
+    # get puzzle and parse data
+    puzzle = Puzzle(year=2023, day=4)
+
+    # parse_input(puzzle.input_data)
+    winning_numbers = get_winning_numbers(puzzle.input_data)
+
+    answer_a = sum(calculate_score(winning_numbers))
+    print(f"{answer_a}")
+    submit(answer_a, part="a", day=4, year=2023)
+
+    # part b:
+    answer_b = 0
+    print(f"{answer_b}")
+    #submit(answer_b, part="b", day=4, year=2023)