mirror of https://github.com/exaloop/codon
46 lines
770 B
Python
46 lines
770 B
Python
# FANNKUCH benchmark
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from math import factorial as fact
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from sys import argv
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from time import time
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def perm(n, i):
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p = [0] * n
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for k in range(n):
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f = fact(n - 1 - k)
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p[k] = i // f
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i = i % f
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for k in range(n - 1, -1, -1):
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for j in range(k - 1, -1, -1):
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if p[j] <= p[k]:
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p[k] += 1
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return p
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n = int(argv[1])
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max_flips = 0
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t0 = time()
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for idx in range(fact(n)):
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p = perm(n, idx)
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flips = 0
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k = p[0]
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while k:
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i = 0
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j = k
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while i < j:
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p[i], p[j] = p[j], p[i]
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i += 1
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j -= 1
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k = p[0]
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flips += 1
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max_flips = max(flips, max_flips)
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print(f'Pfannkuchen({n}) = {max_flips}')
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t1 = time()
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print(t1 - t0)
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