Find longest substring without certain character in python 3-CodePudding

My question is - how can I find a length of the longest substring without certain character?

For example, I want to find a length of the longest substring without letter 'a' in the string 'cbdbabdbcbdacbadbcbbcda' and the answer should be '7' - the longest string without 'a' is 'dbcbbcd'.

What are the possible ways to do it?

CodePudding user response：

Split the string by the certain character, in this case "a", count the lengths of the substrings, and get the maximum.

string = 'cbdbabdbcbdacbadbcbbcda'
avoid = 'a'

longest_substring = max((len(substring) for substring in string.split(avoid)))
print(longest_substring)

This outputs 7.

You can obviously split the comprehension up into multiple lines etc. if that makes it easier to understand.

CodePudding user response：

A regex based approach might use re.findall with the pattern [b-z] :

inp = "cbdbabdbcbdacbadbcbbcda"
longest = sorted(re.findall(r'[b-z] ', inp), key=len, reverse=True)[0]
print(longest)       # dbcbbcd
print(len(longest))  # 7

CodePudding user response：

You can also use a simple for loop to achieve this.

string = 'cbdbabdbcbdacbadbcbbcda'
avoid = 'a'

max_count, curr_count = 0, 0

for char in string:
    if char != avoid:
        curr_count  = 1
    else:
        if curr_count > max_count:
            max_count = curr_count
        curr_count = 0 # Reset curr_count

print(max_count)

Output: