A substring with a length of three and different characters in the leetcode simple question

subject

If a string does not contain any duplicate characters , We call this string good character string .
Give you a string s , Please return s The middle length is 3 Of Good substring The number of .
Be careful , If the same good substring appears more than once , Every time should be included in the answer .
Substring Is a continuous sequence of characters in a string .
Example 1：
Input ：s = “xyzzaz”
Output ：1
explain ： All in all 4 A length of 3 Substring of ：“xyz”,“yzz”,“zza” and “zaz” .
The only length is 3 The good substring is “xyz” .
Example 2：
Input ：s = “aababcabc”
Output ：4
explain ： All in all 7 A length of 3 Substring of ：“aab”,“aba”,“bab”,“abc”,“bca”,“cab” and “abc” .
Good substrings include “abc”,“bca”,“cab” and “abc” .
Tips ：
1 <= s.length <= 100
s​​​​​​ Only lowercase letters .
source ： Power button （LeetCode）

Their thinking

   To determine whether there are duplicate elements, you can use a hash table , Then traverse the string and check one by one 3 Are all the elements different .

class Solution:
    def countGoodSubstrings(self, s: str) -> int:
        if len(s)<3:
            return 0
        i=2
        count=0
        while i<len(s):
            if len(set(s[i-2:i+1]))==3:
                count+=1
            i+=1
        return count