Count the number of max consecutive “a”'s from a string. Python 3

Question

Say that the user inputs:

\"daslakndlaaaaajnjndibniaaafijdnfijdnsijfnsdinifaaaaaaaaaaafnnasm\"

How would you go about finding the highest

Answer 1

I've seen a couple of regex answers in the comments and the other question, so I'm gonna take a different road. Just getting the count can be done many different ways.

from itertools import groupby

inp = 'daslakndlaaaaajnjndibniaaafijdnfijdnsijfnsdinifaaaaaaaaaaafnnasm';
char_groups = groupby(inp, lambda char:char=='a')
counts = [len(list(group)) for char, group in char_groups]
# We know every other element of 'counts' is an 'a' element.
# We just need to know whether to start at zero or one.
# If inp starts with 'a', start at 0. Otherwise start at 1.
max(counts[not inp.startswith('a')::2]) # 11

I'm pretty sure both of the regex answers I've seen will replace every string of 'aa+' with two 'a's. If you only want to replace the longest string of 'a's with 'aa' and leave the rest alone:

char_groups = groupby(inp)
counts = [(char, len(list(group))) for char, group in char_groups]
max_idx = max(range(len(counts)), key=lambda i:counts[i][1] if counts[i][0]=='a' else 0)
result = ''.join(char*count for char, count in counts[:max_idx]) + 'aa' + ''.join(char*count for char, count in counts[max_idx+1:])
# 'daslakndlaaaaajnjndibniaaafijdnfijdnsijfnsdinifaafnnasm'