First solutions I have found, not much tested beside the few doctests:
from itertools import islice
def start_good1(alist, good_ones=4):
"""
Maybe more efficient for Python
>>> start_good = start_good1
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
4
>>> start_good([])
-1
>>> start_good([0, 0])
-1
>>> start_good([0, 0, 0])
-1
>>> start_good([0, 0, 0, 0, 1])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 3])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4])
4
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4, 5])
4
>>> start_good([1, 2, 3, 4])
0
>>> start_good([1, 2, 3])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 0, 4])
-1
"""
for i in xrange(len(alist) - good_ones + 1):
if all(islice(alist, i, i+good_ones)):
return i
return -1
def start_good2(alist, good_ones=4):
"""
Maybe more efficient for Psyco
>>> start_good = start_good2
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
4
>>> start_good([])
-1
>>> start_good([0, 0])
-1
>>> start_good([0, 0, 0])
-1
>>> start_good([0, 0, 0, 0, 1])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 3])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4])
4
>>> start_good([0, 0, 1, 0, 1, 2, 3, 4, 5])
4
>>> start_good([1, 2, 3, 4])
0
>>> start_good([1, 2, 3])
-1
>>> start_good([0, 0, 1, 0, 1, 2, 0, 4])
-1
"""
n_good = 0
for i, el in enumerate(alist):
if alist[i]:
if n_good == good_ones:
return i - good_ones
else:
n_good += 1
else:
n_good = 0
if n_good == good_ones:
return len(alist) - good_ones
else:
return -1
if __name__ == "__main__":
import doctest
doctest.testmod()
print "Doctests done\n"
Bye,
bearophile
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