Maximum count of sub-strings of length K consisting of same characters

Given a string str and an integer k. The task is to count the occurrences of sub-strings of length k that consist of the same characters. There can be multiple such sub-strings possible of length k, choose the count of the one which appears the maximum number of times as the sub-string (non-overlapping) of str.

Examples: 

Input: str = "aaacaabbaa", k = 2 
Output: 3 
"aa" and "bb" are the only sub-strings of length 2 that consist of the same characters. 
"bb" appears only once as a sub-string of str whereas "aa" appears thrice (which is the answer)

Input: str = "abab", k = 2 
Output: 0 

Approach: Iterate over all the characters from 'a' to 'z' and count the number of times a string of length k consisting only of the current character appears as a sub-string of str. Print the maximum of these counts in the end.

Steps to solve the problem:

• Initialize maxSubStr to 0 and n to the size of the string s.
• Iterate over all characters of the English alphabet using a loop from 0 to 25.
• For each character, store it in a variable ch.
• Initialize a variable curr to 0.
• Use another loop to iterate over all possible substrings of length k in the string s.
• If the current character of the string s is not the same as the character ch, continue with the next iteration of the loop.
• If the current character is the same as ch, count the number of consecutive characters in the substring that are the same as ch, using a variable cnt.
• If cnt is not equal to k, continue with the next iteration of the loop.
• If cnt is equal to k, increment the variable curr.
• After the inner loop, update maxSubStr to the maximum of its current value and curr.
• After the outer loop, return maxSubStr as the result.

Below is the implementation of the above approach: 

3

Time Complexity: O(n), where n is the length of the string.
Auxiliary Space: O(1).