49 lines
1.0 KiB
Python
49 lines
1.0 KiB
Python
#!/usr/bin/env python3
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def str_of_signal(signal):
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return ''.join(map(str, signal))
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def apply_pattern(signal, offset=0):
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sums = [None] * (len(signal)-1) + [signal[-1]]
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for i in range(len(signal)-2, -1, -1):
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sums[i] = sums[i+1] + signal[i]
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i = 0
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step = offset + 1
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while i + step < len(signal):
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n = sum(sums[i::4*step])
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n -= sum(sums[i+step::4*step])
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n -= sum(sums[i+2*step::4*step])
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n += sum(sums[i+3*step::4*step])
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signal[i] = abs(n)%10
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i += 1
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step += 1
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signal[i:] = [s % 10 for s in sums[i:]]
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def phase(signal, n, offset=0):
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for i in range(n):
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apply_pattern(signal, offset)
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def preproc(puzzle_input):
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return list(map(int, puzzle_input))
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def partI(signal):
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signal = signal.copy()
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phase(signal, 100)
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return str_of_signal(signal[:8])
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def partII(signal):
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signal = signal * 10**4
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offset = int(str_of_signal(signal[:7]))
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signal = signal[offset:]
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phase(signal, 100, offset)
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return str_of_signal(signal[:8])
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