recipe-475169.py 文件源码

def mix_and_match(limit, items, verbose = False):

    # filter items
    items = [(size, name) for size, name in items if size <= limit]
    # sort them by size
    items.sort(lambda (xsize, xname), (ysize, yname): cmp(xsize, ysize))

    # initialize variables
    added_collections = dict([(set([name]), size) for size, name in items])
    collections = added_collections

    while True:
        if verbose:
            sys.stderr.write("%d\n" % len(collections))

        # find unique combinations of the recent collections 
        new_collections = {}
        for names1, size1 in added_collections.iteritems():
            for size2, name2 in items:
                size3 = size1 + size2
                if size3 > limit:
                    # we can break here as all collections that follow are
                    #  bigger in size due to the sorting above
                    break
                if name2 in names1:
                    continue
                names3 = names1.union(set([name2]))
                if names3 in new_collections:
                    continue
                new_collections[names3] = size3

        if len(new_collections) == 0:
            break

        collections.update(new_collections)
        added_collections = new_collections

    return [(size, names) for names, size in collections.iteritems()]