Java编程实现在线考试系统中的试题选取算法

public List<Question> randomSelectQuestions(List<Question> questionBank, int num) {
    // 创建一个保存选中试题的列表
    List<Question> selectedQuestions = new ArrayList<>();

    // 随机选择试题
    Random random = new Random();
    int size = questionBank.size();
    for (int i = 0; i < num; i++) {
        int index = random.nextInt(size);
        selectedQuestions.add(questionBank.get(index));
    }

    return selectedQuestions;
}

public List<Question> balancedSelectQuestions(List<Question> questionBank, int num) {
    List<Question> selectedQuestions = new ArrayList<>();

    // 统计难度和数量分布
    Map<Integer, Integer> difficultyMap = new HashMap<>();
    for (Question question : questionBank) {
        int difficulty = question.getDifficulty();
        difficultyMap.put(difficulty, difficultyMap.getOrDefault(difficulty, 0) + 1);
    }

    // 计算每个难度应该选择的数量
    int[] targetNums = new int[5]; // 假设难度从1到5，分布为1:2:3:2:1
    int sum = num;
    for (int i = 0; i < 5; i++) {
        targetNums[i] = (int) (num * (1.0 * difficultyMap.getOrDefault(i + 1, 0) / questionBank.size()));
        sum -= targetNums[i];
    }

    // 随机选择试题
    Random random = new Random();
    for (int i = 0; i < 5; i++) {
        List<Question> questions = questionBank.stream().filter(question -> question.getDifficulty() == i + 1).collect(Collectors.toList());
        int size = questions.size();
        for (int j = 0; j < targetNums[i] && j < size; j++) {
            int index = random.nextInt(size);
            selectedQuestions.add(questions.get(index));
        }
    }

    // 补充不足的试题
    while (selectedQuestions.size() < num) {
        int index = random.nextInt(questionBank.size());
        selectedQuestions.add(questionBank.get(index));
    }

    return selectedQuestions;
}