[LeetCode]#1876. Substrings of Size Three with Distinct Characters

Environment: Python 3.8

Key technique: for, if, !=

A string is good if there are no repeated characters.

Given a string s​​​​​, return the number of good substrings of length three in s​​​​​​.

Note that if there are multiple occurrences of the same substring, every occurrence should be counted.

A substring is a contiguous sequence of characters in a string.

Example 1:

Input: s = "xyzzaz"
Output: 1
Explanation: There are 4 substrings of size 3: "xyz", "yzz", "zza", and "zaz".
The only good substring of length 3 is "xyz".


  1. if s[i] != s[i+1] and s[i] != s[i+2] and s[i+1] !=s[i+2], ans+=1.
  2. Return ans


class Solution:
def countGoodSubstrings(self, s):
for i in range(len(s)-2):
if (s[i] != s[i+1] and s[i] != s[i+2] and s[i+1] !=s[i+2]):
return ans