# 1876. Substrings of Size Three with Distinct Characters

## Description

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".


Example 2:

Input: s = "aababcabc"
Output: 4
Explanation: There are 7 substrings of size 3: "aab", "aba", "bab", "abc", "bca", "cab", and "abc".
The good substrings are "abc", "bca", "cab", and "abc".


Constraints:

• 1 <= s.length <= 100
• s​​​​​​ consists of lowercase English letters.

## Solutions

• class Solution {
public int countGoodSubstrings(String s) {
int count = 0, n = s.length();
for (int i = 0; i < n - 2; ++i) {
char a = s.charAt(i), b = s.charAt(i + 1), c = s.charAt(i + 2);
if (a != b && a != c && b != c) {
++count;
}
}
return count;
}
}

• class Solution:
def countGoodSubstrings(self, s: str) -> int:
count, n = 0, len(s)
for i in range(n - 2):
count += s[i] != s[i + 1] and s[i] != s[i + 2] and s[i + 1] != s[i + 2]
return count


• function countGoodSubstrings(s: string): number {
const n: number = s.length;
let count: number = 0;
for (let i: number = 0; i < n - 2; ++i) {
let a: string = s.charAt(i),
b: string = s.charAt(i + 1),
c: string = s.charAt(i + 2);
if (a != b && a != c && b != c) {
++count;
}
}
return count;
}


• class Solution {
/**
* @param String $s * @return Integer */ function countGoodSubstrings($s) {
$cnt = 0; for ($i = 0; $i < strlen($s) - 2; $i++) { if ($s[$i] !=$s[$i + 1] &&$s[$i] !=$s[$i + 2] &&$s[$i + 1] !=$s[$i + 2]) {$cnt++;
}
}
return \$cnt++;
}
}