Advent of Code (Python): solve 2019/22 p1

Author: IsaacG

advent_of_code/2019/d22.py

@@ -0,0 +1,66 @@
+#!/bin/python
+"""Advent of Code, Day 22."""
+# https://www.reddit.com/r/adventofcode/comments/ee0rqi/comment/fbwp0r0/
+
+import collections
+PARSER = str.splitlines
+
+
+def solve(data: list[str], part: int, testing: bool) -> int:
+    """Return a card after shuffling."""
+    want_card = 0 if testing else 2019 if part == 1 else 2020
+    deck_size = 10 if testing else 10007 if part == 1 else 119315717514047
+    # cards = collections.deque(range(deck_size))
+    # position = list(cards).index(want_card)
+    position = want_card
+    for _ in range(1 if part == 1 else 101741582076661):
+        for cmd in data:
+            if cmd == "deal into new stack":
+                # cards.reverse()
+                position = deck_size - 1 - position
+            elif cmd.startswith("cut"):
+                n = int(cmd.split()[-1])
+                # cards.rotate(-n)
+                position = (position - n) % deck_size
+            elif cmd.startswith("deal with increment"):
+                n = int(cmd.split()[-1])
+                # new_cards = [0] * deck_size
+                # for i, card in enumerate(cards):
+                #     new_cards[(i * n) % deck_size] = card
+                # cards = collections.deque(new_cards)
+                position = (position * n) % deck_size
+
+    return position
+
+
+SAMPLE = [
+    """\
+deal with increment 7
+deal into new stack
+deal into new stack""",
+    """\
+cut 6
+deal with increment 7
+deal into new stack""",
+    """\
+deal with increment 7
+deal with increment 9
+cut -2""",
+    """\
+deal into new stack
+cut -2
+deal with increment 7
+cut 8
+cut -4
+deal with increment 7
+cut 3
+deal with increment 9
+deal with increment 3
+cut -1""",
+]
+TESTS = [
+    (1, SAMPLE[0], 0),
+    (1, SAMPLE[1], 3),
+    (1, SAMPLE[2], 6),
+    (1, SAMPLE[3], 9),
+]