Skip to content

3456. Find Special Substring of Length K 👍

  • Time: $O(n)$
  • Space: $O(1)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
class Solution {
 public:
  bool hasSpecialSubstring(string s, int k) {
    int count = 1;

    for (int i = 1; i < s.length(); ++i) {
      if (s[i] == s[i - 1])
        ++count;
      else if (count == k)
        return true;
      else
        count = 1;
    }

    return count == k;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
class Solution {
  public boolean hasSpecialSubstring(String s, int k) {
    int count = 1;

    for (int i = 1; i < s.length(); ++i) {
      if (s.charAt(i) == s.charAt(i - 1))
        ++count;
      else if (count == k)
        return true;
      else
        count = 1;
    }

    return count == k;
  }
}

1
2
3
class Solution:
  def hasSpecialSubstring(self, s: str, k: int) -> bool:
    return any(len(list(group)) == k for _, group in groupby(s))