You are given a string s and an integer k. Your task is to find the maximum difference between the frequency of two characters, freq[a] - freq[b], in a substring subs of s, such that:
subs has a size of at least k.a has an odd frequency in subs.b has an even frequency in subs.Return the maximum difference.
Note that subs can contain more than 2 distinct characters.
Example 1:
Input: s = "12233", k = 4
Output: -1
Explanation:
For the substring "12233", the frequency of '1' is 1 and the frequency of '3' is 2. The difference is 1 - 2 = -1.
Example 2:
Input: s = "1122211", k = 3
Output: 1
Explanation:
For the substring "11222", the frequency of '2' is 3 and the frequency of '1' is 2. The difference is 3 - 2 = 1.
Example 3:
Input: s = "110", k = 3
Output: -1
Constraints:
3 <= s.length <= 3 * 104s consists only of digits '0' to '4'.1 <= k <= s.length