maximum-number-of-occurrences-of-a-substring

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1297. Maximum Number of Occurrences of a Substring (Medium)

Given a string s, return the maximum number of ocurrences of any substring under the following rules:

• The number of unique characters in the substring must be less than or equal to maxLetters.
• The substring size must be between minSize and maxSize inclusive.

 

Example 1:

Input: s = "aababcaab", maxLetters = 2, minSize = 3, maxSize = 4
Output: 2
Explanation: Substring "aab" has 2 ocurrences in the original string.
It satisfies the conditions, 2 unique letters and size 3 (between minSize and maxSize).

Example 2:

Input: s = "aaaa", maxLetters = 1, minSize = 3, maxSize = 3
Output: 2
Explanation: Substring "aaa" occur 2 times in the string. It can overlap.

Example 3:

Input: s = "aabcabcab", maxLetters = 2, minSize = 2, maxSize = 3
Output: 3

Example 4:

Input: s = "abcde", maxLetters = 2, minSize = 3, maxSize = 3
Output: 0

 

Constraints:

• 1 <= s.length <= 10^5
• 1 <= maxLetters <= 26
• 1 <= minSize <= maxSize <= min(26, s.length)
• s only contains lowercase English letters.

Related Topics

[Bit Manipulation] [String]

Hints

Hint 1

Check out the constraints, (maxSize <=26).

Hint 2

This means you can explore all substrings in O(n * 26).

Hint 3

Find the Maximum Number of Occurrences of a Substring with bruteforce.