public class Solution
extends Object
395 - Longest Substring with At Least K Repeating Characters\.
Medium
Given a string `s` and an integer `k`, return _the length of the longest substring of_ `s` _such that the frequency of each character in this substring is greater than or equal to_ `k`.
**Example 1:**
**Input:** s = "aaabb", k = 3
**Output:** 3
**Explanation:** The longest substring is "aaa", as 'a' is repeated 3 times.
**Example 2:**
**Input:** s = "ababbc", k = 2
**Output:** 5
**Explanation:** The longest substring is "ababb", as 'a' is repeated 2 times and 'b' is repeated 3 times.
**Constraints:**
* 1 <= s.length <= 104
* `s` consists of only lowercase English letters.
* 1 <= k <= 105