[알고리즘문제풀기] 문자 개수 세기

문제

내가 작성한 정답

class Solution {
    public int[] solution(String my_string) {
        int[] answer = new int[52];
        char[] al = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',
                'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
        for(int i=0; i<52; i++){
            for(int j=0; j<my_string.length(); j++){
                if(my_string.charAt(j)==al[i]) answer[i]++;
            }
        }
        return answer;
    }
}

다른 사람들의 정답

class Solution {
    public int[] solution(String my_string) {
        int[] answer = new int[52];
        for(int i = 0; i < my_string.length(); i++){
            char c = my_string.charAt(i);
            if(c >= 'a')
                answer[c - 'a' + 26]++;
            else
                answer[c - 'A']++;
        }
        return answer;
    }
}

class Solution {
    public int[] solution(String my_string) {
        int[] answer = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

        for(char ch: my_string.toCharArray()) {
            answer[ch - 'A' - (Character.isLowerCase(ch)?6:0)]++;
        }
        return answer;
    }
}