On 08/12/2010 10:51 PM, John Posner wrote:
> On 8/12/2010 9:22 AM, Dave Angel wrote:
>>>
>>> Now you have to find the largest number below 120, which you can
>>> easily do with brute force
>
> Dept of overkill, iterators/generators division ...
>
> -John
>
> #------------------
> from itertools import imap, product, ifilter
> from operator import mul
>
> box_sizes = (6, 9, 20)
>
> def sum_product(s1, s2):
> """
> return "scalar product" of two sequences
> """
> return sum(imap(mul, s1, s2))
>
> def reachables(target):
> """
> return generator of numbers that are <= target
> and are valid linear combos of McNuggets
> """
> candidate_box_counts = product(
> xrange(target/box_sizes[0] + 1),
> xrange(target/box_sizes[1] + 1),
> xrange(target/box_sizes[2] + 1),
> )
Couldn't this be rewritten as:
candidate_box_counts = product(
* [ xrange(target/sizes + 1) for size in box_sizes ]
)
>
> gen = (sum_product(box_sizes, tup)
> for tup in candidate_box_counts)
>
> return (ifilter(lambda val, tgt=target: val < tgt,
> gen))
>
> if __name__ == "__main__":
> tgt = 120 # thanks, Dave Angel
> unreachables = set(xrange(tgt)) - set(reachables(tgt))
> print "Max unreachable:", max(unreachables)
--
http://mail.python.org/mailman/listinfo/python-list
