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@@ -0,0 +1,42 @@
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+#!/usr/bin/env python3
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+import sys
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+from itertools import chain, islice, pairwise
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+
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+def permute(num):
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+ num = (num ^ num << 6) & 0xffffff
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+ num ^= num >> 5
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+ return (num ^ num << 11) & 0xffffff
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+
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+def prices(num):
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+ while True:
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+ yield num % 10
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+ num = permute(num)
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+
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+def window(seq, n):
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+ win = tuple(islice(seq, n))
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+ yield win
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+ for elem in seq:
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+ win = win[1:] + (elem,)
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+ yield win
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+
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+def sequence_prices(num):
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+ seen = {}
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+ for nums in window(islice(prices(num), 2001), 5):
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+ diffs = tuple(b - a for a, b in pairwise(nums))
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+ seen.setdefault(diffs, nums[-1])
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+ return seen
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+
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+def max_prices(initials):
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+ all_seq_prices = list(map(sequence_prices, initials))
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+ sequences = set(chain.from_iterable(all_seq_prices))
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+ return max(sum(seq_prices.get(seq, 0) for seq_prices in all_seq_prices)
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+ for seq in sequences)
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+
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+def nth(num, n):
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+ for _ in range(n):
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+ num = permute(num)
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+ return num
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+
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+initials = list(map(int, sys.stdin))
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+print(sum(nth(num, 2000) for num in initials))
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+print(max_prices(initials))
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Taddeus Kroes