Files
AdventOfCode/2020/solutions/day_22.py
2020-12-25 23:50:29 +01:00

111 lines
3.3 KiB
Python

"""AOC 2020 Day 22"""
import pathlib
import time
import collections
import itertools
TEST_INPUT = """Player 1:
9
2
6
3
1
Player 2:
5
8
4
7
10"""
def read_input(input_path: str) -> str:
"""take input file path and return a str with the file's content"""
with open(input_path, 'r') as input_file:
input_data = input_file.read().strip()
return input_data
def extract(input_data: str) -> tuple:
"""take input data and return the appropriate data structure"""
deck1, deck2 = input_data.split('\n\n')
deck1, deck2 = deck1.splitlines(), deck2.splitlines()
deck1 = collections.deque(map(int, deck1[1:]))
deck2 = collections.deque(map(int, deck2[1:]))
return deck1, deck2
def play_space_cards(deck1: collections.deque, deck2: collections.deque) -> collections.deque:
"""return the winner's deck after a space cards game"""
assert len(deck1) == len(deck2)
while deck1 and deck2:
card1, card2 = deck1.popleft(), deck2.popleft()
assert card1 != card2
if card1 > card2:
deck1.extend((card1, card2))
else:
deck2.extend((card2, card1))
return deck1 if deck1 else deck2
def play_recursive_space_cards(deck1: collections.deque, deck2: collections.deque) -> tuple:
"""return the winner and its deck after a recursive space cards game"""
configurations = set()
while deck1 and deck2:
current_config = (tuple(deck1), tuple(deck2))
if current_config in configurations:
return 1, deck1
configurations.add(current_config)
card1, card2 = deck1.popleft(), deck2.popleft()
assert card1 != card2
if card1 <= len(deck1) and card2 <= len(deck2):
sub_deck1 = collections.deque(itertools.islice(deck1, card1))
sub_deck2 = collections.deque(itertools.islice(deck2, card2))
winner, _ = play_recursive_space_cards(sub_deck1, sub_deck2)
else:
winner = 1 if card1 > card2 else 2
if winner == 1:
deck1.extend((card1, card2))
else:
deck2.extend((card2, card1))
return (1, deck1) if deck1 else (2, deck2)
def part1(entries: tuple) -> int:
"""part1 solver"""
deck1, deck2 = entries[0].copy(), entries[1].copy()
winner = play_space_cards(deck1, deck2)
return sum(index * card for index, card in enumerate(reversed(winner), 1))
def part2(entries: tuple) -> str:
"""part2 solver"""
deck1, deck2 = entries
_, winner = play_recursive_space_cards(deck1, deck2)
return sum(index * card for index, card in enumerate(reversed(winner), 1))
def test_input_day_22():
"""pytest testing function"""
entries = extract(TEST_INPUT)
assert part1(entries) == 306
assert part2(entries) == 291
def test_bench_day_22(benchmark):
"""pytest-benchmark function"""
benchmark(main)
def main():
"""main function"""
input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
start_time = time.time()
input_data = read_input(input_path)
entries = extract(input_data)
print("Part 1: %d" % part1(entries))
print("Part 2: %s" % part2(entries))
end_time = time.time()
print("Execution time: %f" % (end_time-start_time))
if __name__ == "__main__":
main()