Given a string s and an integer k, return the number of substrings in s of length k with no repeated characters.

 

Example 1:

Input: s = "havefunonleetcode", k = 5
Output: 6
Explanation: There are 6 substrings they are: 'havef','avefu','vefun','efuno','etcod','tcode'.

Example 2:

Input: s = "home", k = 5
Output: 0
Explanation: Notice k can be larger than the length of s. In this case, it is not possible to find any substring.

 

Constraints:

• 1 <= s.length <= 104
• s consists of lowercase English letters.
• 1 <= k <= 104