Python - Longest Substring Length of K

Given a String and a character K, find longest substring length of K.

Input : test_str = ‘abcaaaacbbaa’, K = b
Output : 2
Explanation : b occurs twice, 2 > 1.

Input : test_str = ‘abcaacccbbaa’, K = c
Output : 3
Explanation : Maximum times c occurs is 3.

Method #1 : Using loop

This is brute way to solve this problem, in this, when K is encountered, counter is maintained till other character occurs, and count is noted, the maximum of these counts is kept and is returned as result.

Python3

# Python3 code to demonstrate working of  
# Longest Substring of K 
# Using loop 
  
# initializing string 
test_str = 'abcaaaacbbaa'
  
# printing original String 
print("The original string is : " + str(test_str)) 
  
# initializing K  
K = 'a'
  
cnt = 0
res = 0
for idx in range(len(test_str)): 
      
    # increment counter on checking 
    if test_str[idx] == K: 
        cnt += 1
    else: 
        cnt = 0
          
    # retaining max 
    res = max(res, cnt) 
  
# printing result  
print("The Longest Substring Length : " + str(res))  

Output

The original string is : abcaaaacbbaa
The Longest Substring Length : 4

Method #2 : Using findall() + max()

In this, we get all the possible substrings of K using findall() and max() is used over it to get maximum length with len as key.

Python3

# Python3 code to demonstrate working of  
# Longest Substring of K 
# Using findall() + max() 
import re 
  
# initializing string 
test_str = 'abcaaaacbbaa'
  
# printing original String 
print("The original string is : " + str(test_str)) 
  
# initializing K  
K = 'a'
  
# getting all substrings 
res = re.findall(r'' + K + '+', test_str) 
  
# getting maximum of substrings Length 
res = len(max(res, key = len)) 
  
# printing result  
print("The Longest Substring Length : " + str(res))  

Output

The original string is : abcaaaacbbaa
The Longest Substring Length : 4

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Python – Longest Substring Length of K

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