day02_rock_paper_scissors.py

#!/usr/bin/env python3

from enum import Enum


class Shape(Enum):
    ROCK = 1
    PAPPER = 2
    SCISSORS = 3


def main(strategy: str) -> None:
    score = 0
    for turn in strategy.splitlines():
        opponent, you = parse(turn)
        score += outcome(opponent, you) + you.value
    print("Part One:")
    print(score)

    score = 0
    for turn in strategy.splitlines():
        opponent, you = parse2(turn)
        score += outcome(opponent, you) + you.value
    print("Part Two:")
    print(score)


def parse(turn: str) -> tuple[Shape, Shape]:
    first, second = turn.split()
    opponent = {"A": Shape.ROCK, "B": Shape.PAPPER, "C": Shape.SCISSORS}[first]
    you = {"X": Shape.ROCK, "Y": Shape.PAPPER, "Z": Shape.SCISSORS}[second]
    return opponent, you


def parse2(turn: str) -> tuple[Shape, Shape]:
    first, second = turn.split()
    opponent = {"A": Shape.ROCK, "B": Shape.PAPPER, "C": Shape.SCISSORS}[first]
    you = [
        {"X": Shape.SCISSORS, "Y": Shape.ROCK, "Z": Shape.PAPPER}[second],
        {"X": Shape.ROCK, "Y": Shape.PAPPER, "Z": Shape.SCISSORS}[second],
        {"X": Shape.PAPPER, "Y": Shape.SCISSORS, "Z": Shape.ROCK}[second],
    ][opponent.value - 1]
    return opponent, you


def outcome(opponent: Shape, you: Shape) -> int:
    if opponent == you:
        return 3
    return [
        6 if you == Shape.PAPPER else 0,  # opponent = Shape.ROCK
        6 if you == Shape.SCISSORS else 0,  # opponent = Shape.PAPPER
        6 if you == Shape.ROCK else 0,  # opponent = Shape.SCISSORS
    ][opponent.value - 1]


if __name__ == "__main__":
    INPUT = """A Y
B X
C Z
"""

    main(INPUT)