알고리즘을 어떻게 짜는지에 따라 가독성 과 수행속도가 엄청나게 차이가 난다..

List , sort 사용

import java.util.List;
import java.util.stream.Collectors;

class Solution {
    public int solution(String before, String after) {
        List<Character> beforeList = before.chars().mapToObj(c -> (char) c).collect(Collectors.toList());
        List<Character> afterList = after.chars().mapToObj(c -> (char) c).collect(Collectors.toList());

        beforeList.sort(null);
        afterList.sort(null);

        if (afterList.equals(beforeList)) {
            return 1;
        } else {
            return 0;
        }
    }
}

계수정렬 사용

class Solution {
    public int solution(String before, String after) {
        int[] beforeArr = countCharNum(before);
        int[] afterArr = countCharNum(after);

        for (int i = 0; i < afterArr.length; i++) {
            int bi = beforeArr[i];
            int ai = afterArr[i];

            if (bi != ai) {
                return 0;
            }
        }

        return 1;
    }

    private int[] countCharNum(String str) {
        int[] rtArr = new int[30];

        for (int i = 0; i < str.length(); i++) {
            int idx = str.charAt(i) - 'a';
            rtArr[idx]++;
        }

        return rtArr;
    }
}