shuffling_decks_of_cards.py

def is_sorted(a):
        for (c,d) in enumerate(a):
                if c!=d:
                        return False
        return True

def shuffle(a):
        a_len=len(a)
        map(a.extend,zip(a[:a_len/2],a[a_len/2:a_len]))
        del a[:a_len]

def try_deck(size):     
        a=range(size)
        shuffle(a)
        i=1
        while not is_sorted(a):
                shuffle(a)
                i+=1
        return i

for Z in range(2,1025,2):
        print Z,try_deck(Z)