3121. Count the Number of Special Characters II

/**
 * Problem: LeetCode 3121 - Count the Number of Special Characters II
 * Difficulty: Medium
 * Language: Java
 * Author: CodeByTushu
 */
import java.util.Arrays;

class Solution {
    public int numberOfSpecialChars(String word) {
        int[] lastLower = new int[26];
        int[] firstUpper = new int[26];
        Arrays.fill(lastLower, -1);
        Arrays.fill(firstUpper, -1);

        int n = word.length();
        for (int i = 0; i < n; i++) {
            char ch = word.charAt(i);
            if (ch >= 'a' && ch <= 'z') {
                lastLower[ch - 'a'] = i;
            } else if (ch >= 'A' && ch <= 'Z') {
                int idx = ch - 'A';
                if (firstUpper[idx] == -1) {
                    firstUpper[idx] = i;
                }
            }
        }

        int specialCount = 0;
        for (int i = 0; i < 26; i++) {
            if (lastLower[i] != -1 && firstUpper[i] != -1 && lastLower[i] < firstUpper[i]) {
                specialCount++;
            }
        }

        return specialCount;
    }
}

"""
Problem: LeetCode 3121 - Count the Number of Special Characters II
Difficulty: Medium
Language: Python
Author: CodeByTushu
"""
class Solution:
    def numberOfSpecialChars(self, word: str) -> int:
        last_lower = [-1] * 26
        first_upper = [-1] * 26

        for i, ch in enumerate(word):
            if 'a' <= ch <= 'z':
                last_lower[ord(ch) - ord('a')] = i
            elif 'A' <= ch <= 'Z':
                idx = ord(ch) - ord('A')
                if first_upper[idx] == -1:
                    first_upper[idx] = i

        special_count = 0
        for i in range(26):
            if last_lower[i] != -1 and first_upper[i] != -1 and last_lower[i] < first_upper[i]:
                special_count += 1

        return special_count

/**
 * Problem: LeetCode 3121 - Count the Number of Special Characters II
 * Difficulty: Medium
 * Language: C++
 * Author: CodeByTushu
 */
#include <string>
#include <vector>

using namespace std;

class Solution {
public:
    int numberOfSpecialChars(string word) {
        vector<int> lastLower(26, -1);
        vector<int> firstUpper(26, -1);

        int n = word.size();
        for (int i = 0; i < n; i++) {
            char ch = word[i];
            if (ch >= 'a' && ch <= 'z') {
                lastLower[ch - 'a'] = i;
            } else if (ch >= 'A' && ch <= 'Z') {
                int idx = ch - 'A';
                if (firstUpper[idx] == -1) {
                    firstUpper[idx] = i;
                }
            }
        }

        int specialCount = 0;
        for (int i = 0; i < 26; i++) {
            if (lastLower[i] != -1 && firstUpper[i] != -1 && lastLower[i] < firstUpper[i]) {
                specialCount++;
            }
        }

        return specialCount;
    }
};

/**
 * Problem: LeetCode 3121 - Count the Number of Special Characters II
 * Difficulty: Medium
 * Language: JavaScript
 * Author: CodeByTushu
 */
/**
 * @param {string} word
 * @return {number}
 */
var numberOfSpecialChars = function(word) {
    const lastLower = new Int32Array(26).fill(-1);
    const firstUpper = new Int32Array(26).fill(-1);

    const n = word.length;
    for (let i = 0; i < n; i++) {
        const code = word.charCodeAt(i);
        if (code >= 97 && code <= 122) { // 'a' - 'z'
            lastLower[code - 97] = i;
        } else if (code >= 65 && code <= 90) { // 'A' - 'Z'
            const idx = code - 65;
            if (firstUpper[idx] === -1) {
                firstUpper[idx] = i;
            }
        }
    }

    let specialCount = 0;
    for (let i = 0; i < 26; i++) {
        if (lastLower[i] !== -1 && firstUpper[i] !== -1 && lastLower[i] < firstUpper[i]) {
            specialCount++;
        }
    }

    return specialCount;
};