Find maximum length of consecutive repeated numbers in a list

Question

My question is how to find the maximum length of consecutive repeated numbers (or elements in general) in a list. I wrote the following function which works fine but I was w

Answer 1

You can use itertools.

In [8]: import itertools

In [9]: z = [(x[0], len(list(x[1]))) for x in itertools.groupby(a)]

In [10]: z
Out[10]: [(1, 2), (2, 3), (3, 1)]

Tuples are in (item, count) format. If there are multiple runs of a given number, this will group them accordingly as well. See below.

In [11]: a = [1,1,1,1,1,2,2,2,2,2,1,1,1,3,3]

In [12]: z = [(x[0], len(list(x[1]))) for x in itertools.groupby(a)]

In [13]: z
Out[13]: [(1, 5), (2, 5), (1, 3), (3, 2)]

Getting the max value isn't that hard from here.

In [15]: max(z, key=lambda x:x[1])[1]
Out[15]: 5

Answer 2

longest_fragment = 0
current_fragment = 0

a = int(input())
last_input = a # why do I assign last_input here?
while a:
    if a == last_input:
        current_fragment += 1
    else:  # why is current_fragment assigned 1 in this clause?
        if current_fragment > longest_fragment:
            longest_fragment = current_fragment
            current_fragment = 1
    last_input = a
    a = int(input())

longest_fragment = max(longest_fragment, current_fragment) 
# why didn't i use max in the loop?
# why am I checking again down here anyway?

print('The longest fragment was:', longest_fragment)