3120

3120. Count the Number of Special Characters I (Easy)

You are given a string word. A letter is called special if it appears both in lowercase and uppercase in word.

Return the number of special letters in word.

 

Example 1:

Input: word = "aaAbcBC"

Output: 3

Explanation:

The special characters in word are 'a', 'b', and 'c'.

Example 2:

Input: word = "abc"

Output: 0

Explanation:

No character in word appears in uppercase.

Example 3:

Input: word = "abBCab"

Output: 1

Explanation:

The only special character in word is 'b'.

 

Constraints:

• 1 <= word.length <= 50
• word consists of only lowercase and uppercase English letters.

Similar Questions:

• Detect Capital (Easy)

Hints:

• The constraints are small. For all the 56 characters, check if they are present in word.

Solution 1.

// OJ: https://leetcode.com/problems/count-the-number-of-special-characters-i
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int numberOfSpecialChars(string s) {
        int cnt[26] = {}, ans = 0;
        for (char c : s) {
            if (islower(c)) cnt[c - 'a'] |= 1;
            else cnt[c - 'A'] |= 2;
        }
        for (int i = 0; i < 26; ++i) {
            ans += cnt[i] == 3;
        }
        return ans;
    }
};