1876

1876. Substrings of Size Three with Distinct Characters (Easy)

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.

Companies:
Quora

Related Topics:
String

Solution 1.

// OJ: https://leetcode.com/problems/substrings-of-size-three-with-distinct-characters/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int countGoodSubstrings(string s) {
        int ans = 0;
        for (int i = 0; i+ 2 < s.size(); ++i) {
            ans += s[i] != s[i+1] && s[i+1] != s[i+2] && s[i] != s[i+2];
        }
        return ans;
    }
};