27 lines
876 B
Python
27 lines
876 B
Python
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from helpers import *
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lines = read_day(25).split('\n')
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snafu_digits = {'=':-2, '-':-1, '0':0, '1':1, '2':2}
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# minimal_snafus = [-2]
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# for i in range(1, 50):
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# minimal_snafus.append(minimal_snafus[-1] + (-2 * (5**i)))
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# print(minimal_snafus)
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def snafu_to_decimal(s: str) -> int:
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return sum((snafu_digits[v] * (5**i) for i,v in enumerate(reversed(s))))
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def decimal_to_snafu(i: int) -> str:
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# We don't want to constantly flip addition/subtraction, so start with biggest number and subtract
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digits = 0
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maximal = 0
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while i > maximal:
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maximal += 2 * (5**digits)
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digits += 1
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base5 = np.base_repr(maximal-i, 5)
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s = ['2'] * digits
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for i,d in enumerate(reversed(base5)):
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s[i] = {'0':'2', '1':'1', '2':'0', '3':'-', '4':'='}[d]
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return ''.join(reversed(s))
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# print(decimal_to_snafu(1747))
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print(f'Part 1: {decimal_to_snafu(sum((snafu_to_decimal(l) for l in lines)))}')
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