Counting distinct lists in a list I'm trying to remove the duplicate from the list and count the list after removing the duplicates 

seq = [[1,2,3], [1,2,3], [2,3,4], [4,5,6]]
new_seq = [[1,2,3], [2,3,4], [4,5,6]]
count = 3 


My code takes around 23 seconds for around 66,000 lists in a list 

How can I make my code faster?

def unique(seq):
    new_seq = []
    count = 0
    for i in seq:
        if i not in new_seq:
            new_seq.append(i)
            count += 1
    return count
Your function is slow because it is O(n2): each element being added to new_seq has to be compared against every previously added element.

To deduplicate a sequence, use a set.  Constructing the set is only O(n) because it uses hashing.

Then, to obtain the size of the set, use len().

def unique(seq):
    return len(set(tuple(element) for element in seq))