2272 - Substring With Largest Variance\.

Hard

The variance of a string is defined as the largest difference between the number of occurrences of any 2 characters present in the string. Note the two characters may or may not be the same.

Given a string s consisting of lowercase English letters only, return the largest variance possible among all substrings of s.

A substring is a contiguous sequence of characters within a string.

Example 1:

Input: s = "aababbb"

Output: 3

Explanation: All possible variances along with their respective substrings are listed below:

• Variance 0 for substrings "a", "aa", "ab", "abab", "aababb", "ba", "b", "bb", and "bbb".

• Variance 1 for substrings "aab", "aba", "abb", "aabab", "ababb", "aababbb", and "bab".

• Variance 2 for substrings "aaba", "ababbb", "abbb", and "babb".

• Variance 3 for substring "babbb".

Since the largest possible variance is 3, we return it.

Example 2:

Input: s = "abcde"

Output: 0

Explanation: No letter occurs more than once in s, so the variance of every substring is 0.

Constraints:

• <code>1 <= s.length <= 10⁴</code>

• s consists of lowercase English letters.