DEV Community

Cover image for 3121. Count the Number of Special Characters II
MD ARIFUL HAQUE
MD ARIFUL HAQUE

Posted on β€’ Edited on

3121. Count the Number of Special Characters II

3121. Count the Number of Special Characters II

Easy

You are given a string word. A letter c is called special if it appears both in lowercase and uppercase in word, and every lowercase occurrence of c appears before the first uppercase occurrence of c.

Return the number of special letters in word.

Example 1:

  • Input: word = "aaAbcBC"
  • Output: 3
  • Explanation: The special characters are 'a', 'b', and 'c'.

Example 2:

Input: word = "abc"
Output: 0
Explanation: There are no special characters in word.

Example 3:

Input: "AbBCab"
Output: [0,1]
Explanation: There are no special characters in word.

Constraints:

  • 1 <= word.length <= 2 * 105
  • word consists of only lowercase and uppercase English letters.

Solution:

class Solution {

    /**
     * @param String $word
     * @return Integer
     */
    function numberOfSpecialChars($word) {
        $first = array_fill(0, ord('z') + 1, 0);
        $last = array_fill(0, ord('z') + 1, 0);
        for ($i = 1; $i <= strlen($word); ++$i) {
            $j = ord($word[$i - 1]);
            if ($first[$j] == 0) {
                $first[$j] = $i;
            }
            $last[$j] = $i;
        }
        $ans = 0;
        for ($i = 0; $i < 26; ++$i) {
            if ($last[ord('a') + $i] && $first[ord('A') + $i] && $last[ord('a') + $i] < $first[ord('A') + $i]) {
                ++$ans;
            }
        }
        return $ans;
    }
}
Enter fullscreen mode Exit fullscreen mode

Contact Links

If you found this series helpful, please consider giving the repository a star on GitHub or sharing the post on your favorite social networks 😍. Your support would mean a lot to me!

Image of Docusign

πŸ› οΈ Bring your solution into Docusign. Reach over 1.6M customers.

Docusign is now extensible. Overcome challenges with disconnected products and inaccessible data by bringing your solutions into Docusign and publishing to 1.6M customers in the App Center.

Learn more

Top comments (0)

Sentry image

See why 4M developers consider Sentry, β€œnot bad.”

Fixing code doesn’t have to be the worst part of your day. Learn how Sentry can help.

Learn more