Leet code problem 1876: – Substrings of Size Three with Distinct Characters

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.

Flow Diagram: –

Solution: –

class Solution {
    public int countGoodSubstrings(String s) {
        int n = s.length();
        int ans = 0;
        for(int i = 0; i < n - 2; i++) {
            char c1 = s.charAt(i);
            char c2 = s.charAt(i + 1);
            char c3 = s.charAt(i + 2);
            if(c1 == c2 || c2 == c3 || c1 == c3) continue;
            ans++;
        }
        return ans;
    }
}