Description:
Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.
Example 1:
Input:
s = "aaabb", k = 3
Output:
3
The longest substring is "aaa", as 'a' is repeated 3 times.
Example 2:
Input:
s = "ababbc", k = 2
Output:
5
The longest substring is "ababb", as 'a' is repeated 2 times and 'b' is repeated 3 times.
nijilong1224
commented
5 years ago 
LeeMax117
Description: Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.
Example 1:
Input: s = "aaabb", k = 3
Output: 3
The longest substring is "aaa", as 'a' is repeated 3 times. Example 2:
Input: s = "ababbc", k = 2
Output: 5
The longest substring is "ababb", as 'a' is repeated 2 times and 'b' is repeated 3 times.
Process: