3121. Count the Number of Special Characters II

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3121. Count the Number of Special Characters II

Description

You are given a string word. A letterc 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:

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Input: word = "aaAbcBC"

Output: 3

Explanation:

The special characters are `'a'`, `'b'`, and `'c'`.

Example 2:

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Input: word = "abc"

Output: 0

Explanation:

There are no special characters in `word`.

Example 3:

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Input: word = "AbBCab"

Output: 0

Explanation:

There are no special characters in `word`.

Constraints:

  • 1 <= word.length <= 2 * 10^5
  • word consists of only lowercase and uppercase English letters.

Hints/Notes

  • N/A

Solution

Language: C++

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class Solution {
public:
    int numberOfSpecialChars(string word) {
        map<int, int> lower;
        map<int, int> higher;
        for (int i = 0; i < word.size(); i++) {
            char c = word[i];
            if (c >= 'A' && c <= 'Z' && !higher.contains(c - 'A')) {
                higher[c - 'A'] = i;
            } else if (c >= 'a' && c <= 'z') {
                lower[c - 'a'] = i;
            }
        }
        int res = 0;
        for (int i = 0; i < 26; i++) {
            if (higher.contains(i) && lower.contains(i) && higher[i] > lower[i]) {
                res++;
            }
        }
        return res;
    }
};