advent-of-code/2021/d21/ex1/ex1.py

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2021-12-21 15:04:43 +01:00
#!/usr/bin/env python
import itertools
import sys
from typing import Iterable, Iterator, List, NamedTuple, Tuple, TypeVar
T = TypeVar("T")
def grouper(iterable: Iterable[T], n: int) -> Iterator[Tuple[T, ...]]:
args = [iter(iterable)] * n
return itertools.zip_longest(*args)
def take(n: int, iterable: Iterable[T]) -> List[T]:
return list(itertools.islice(iterable, n))
class PlayerStats(NamedTuple):
position: int
score: int
class GameState(NamedTuple):
p1: PlayerStats
p2: PlayerStats
total_rolls: int
WINNING_SCORE = 1000
def solve(input: List[str]) -> int:
def parse() -> Tuple[int, int]:
p1, p2 = input[0].split(" ")[-1], input[1].split(" ")[-1]
return int(p1), int(p2)
def deterministic_die() -> Iterator[int]:
return itertools.cycle(range(1, 100 + 1))
def do_turn(stats: PlayerStats, rolls: Iterator[int]) -> PlayerStats:
position, score = stats
roll = sum(take(3, rolls))
position = ((position - 1 + roll) % 10) + 1
score += position
return PlayerStats(position, score)
def play_to_end(intial_state: GameState) -> GameState:
p1, p2, total_rolls = intial_state
die_rolls = deterministic_die()
while True:
p1 = do_turn(p1, die_rolls)
total_rolls += 3
if p1.score >= WINNING_SCORE:
break
p2 = do_turn(p2, die_rolls)
total_rolls += 3
if p2.score >= WINNING_SCORE:
break
return GameState(p1, p2, total_rolls)
position1, position2 = parse()
p1, p2, total_rolls = play_to_end(
GameState(PlayerStats(position1, 0), PlayerStats(position2, 0), 0)
)
# The loser *must* have the lowest score
return min(p1.score, p2.score) * total_rolls
def main() -> None:
input = [line.strip() for line in sys.stdin.readlines()]
print(solve(input))
if __name__ == "__main__":
main()