Question

1876. Substrings of Size Three with Distinct Characters

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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

Solution 1

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

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;
  }
}

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++;
  }
}