75 lines
1.9 KiB
Python
75 lines
1.9 KiB
Python
from __future__ import annotations
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import sys
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class Number:
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current: int
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value: int
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def __init__(self, value: int):
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self.current = 0
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self.value = value
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def __str__(self):
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return str(self.value)
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def __repr__(self):
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return str(self)
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def decrypt(numbers: list[Number], key: int, rounds: int) -> int:
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numbers = numbers.copy()
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original = numbers.copy()
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for index, number in enumerate(numbers):
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number.current = index
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for _ in range(rounds):
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for number in original:
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index = number.current
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offset = (number.value * key) % (len(numbers) - 1)
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target = index + offset
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# need to wrap
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if target >= len(numbers):
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target = offset - (len(numbers) - index) + 1
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for number_2 in numbers[target:index]:
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number_2.current += 1
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numbers = (
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numbers[:target]
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+ [number]
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+ numbers[target:index]
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+ numbers[index + 1 :]
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)
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else:
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for number_2 in numbers[index : target + 1]:
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number_2.current -= 1
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numbers = (
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numbers[:index]
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+ numbers[index + 1 : target + 1]
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+ [number]
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+ numbers[target + 1 :]
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)
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number.current = target
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index_of_0 = next(
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filter(lambda index: numbers[index].value == 0, range(len(numbers)))
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)
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return sum(
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numbers[(index_of_0 + offset) % len(numbers)].value * key
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for offset in (1000, 2000, 3000)
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)
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numbers = [Number(int(x)) for i, x in enumerate(sys.stdin.readlines())]
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answer_1 = decrypt(numbers, 1, 1)
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print(f"answer 1 is {answer_1}")
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answer_2 = decrypt(numbers, 811589153, 10)
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print(f"answer 2 is {answer_2}")
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