open-lock.py

def window(seq, n=2):
    "Returns a sliding window (of width n) over data from the iterable"
    "   s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ...                   "
    it = iter(seq)
    result = tuple(islice(it, n))
    if len(result) == n:
        yield result
    for elem in it:
        result = result[1:] + (elem,)
        yield result
        
def lock_is_open(combo, tumbler):
    "Check if the tumbler contains the combination based on"
    "a simple combination lock algorithm"
    
    # grab the last number
    final = tumbler[-1]
    
    # cut the list down to only the numbers that are "edges", 
    # i.e. numbers where the lock changed direction
    #
    # on a traditional lock, you enter the combination and then 
    # attempt to open the lock to see if the final digit is correct. 
    # since there is no explicit “open” command in this case, tack 
    # on the final number (which represents the current setting of 
    # the Nest) before checking to see if we have a match.
    check = [x[1] for x in window(tumbler,3) if max(x) == x[1] or min(x) == x[1]] + [final]

    # convert the list to check into windows of len(combo) size
    # this allows us to use a simple "in" operator to check if the combo
    # is inside the list
    check = [x for x in window(check,len(combo))]
    
    # is the combo present in the tumbler?
    return (tuple(combo) in check)