230523 메뉴 리뉴얼

private List<String> answerList = new ArrayList<>();
private Map<String, Integer> hashMap = new HashMap<>();

public String[] solution(String[] orders, int[] course) {
    sortOrders(orders);
    generateCombinations(orders, course);
    
    Collections.sort(answerList);
    return answerList.toArray(new String[0]);
}

private void sortOrders(String[] orders) {
    for (int i = 0; i < orders.length; i++) {
        char[] arr = orders[i].toCharArray();
        Arrays.sort(arr);
        orders[i] = String.valueOf(arr);
    }
}

private void generateCombinations(String[] orders, int[] course) {
    for (int courseLength : course) {
        for (String order : orders) {
            combination("", order, courseLength);
        }
        checkCondition();
        hashMap.clear();
    }
}

private void combination(String order, String others, int count) {
    if (count == 0) {
        hashMap.put(order, hashMap.getOrDefault(order, 0) + 1);
        return;
    }

    for (int i = 0; i < others.length(); i++) {
        combination(order + others.charAt(i), others.substring(i + 1), count - 1);
    }
}

private void checkCondition() {
    if (!hashMap.isEmpty()) {
        int max = Collections.max(hashMap.values());
        
        if (max > 1) {
            for (String key : hashMap.keySet()) {
                if (hashMap.get(key) == max)
                    answerList.add(key);
            }
        }
    }
}

출처:https://school.programmers.co.kr/learn/courses/30/lessons/72411