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package model;
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import java.util.List;
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import java.util.ArrayList;
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import java.util.Set;
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import java.util.HashSet;
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import java.util.Arrays;
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import java.util.Random;
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import java.text.DecimalFormat;
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public class QuestionGenerator {
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private Random random = new Random();
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private DecimalFormat df = new DecimalFormat("#.##"); // 保留两位小数的格式化器
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public List<Question> generateQuestions(int count, String difficulty) {
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List<Question> questions = new ArrayList<>();
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Set<String> existingQuestions = new HashSet<>();
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while (questions.size() < count) {
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Question question = generateQuestion(difficulty);
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String questionKey = question.getQuestion() + Arrays.toString(question.getOptions());
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if (!existingQuestions.contains(questionKey)) {
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questions.add(question);
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existingQuestions.add(questionKey);
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}
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}
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return questions;
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}
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private Question generateQuestion(String difficulty) {
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switch (difficulty) {
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case "小学":
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return generatePrimaryQuestion();
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case "初中":
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return generateMiddleSchoolQuestion();
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case "高中":
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return generateHighSchoolQuestion();
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default:
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return generatePrimaryQuestion();
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}
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}
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private Question generatePrimaryQuestion() {
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int num1 = random.nextInt(50) + 1;
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int num2 = random.nextInt(50) + 1;
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int num3 = random.nextInt(50) + 1;
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char[] operators = {'+', '-', '*', '/'};
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char operator1 = operators[random.nextInt(operators.length)];
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char operator2 = operators[random.nextInt(operators.length)];
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String question;
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double correctAnswer;
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// 随机决定是否使用括号
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if (random.nextBoolean()) {
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// 有括号的情况
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switch (random.nextInt(3)) {
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case 0: // (a op b) op c
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correctAnswer = calculate(calculate(num1, num2, operator1), num3, operator2);
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question = "(" + num1 + " " + getOperatorSymbol(operator1) + " " + num2 + ") " +
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getOperatorSymbol(operator2) + " " + num3 + " = ?";
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break;
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case 1: // a op (b op c)
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correctAnswer = calculate(num1, calculate(num2, num3, operator2), operator1);
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question = num1 + " " + getOperatorSymbol(operator1) + " (" + num2 + " " +
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getOperatorSymbol(operator2) + " " + num3 + ") = ?";
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break;
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default: // 无括号
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correctAnswer = calculate(calculate(num1, num2, operator1), num3, operator2);
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question = num1 + " " + getOperatorSymbol(operator1) + " " + num2 + " " +
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getOperatorSymbol(operator2) + " " + num3 + " = ?";
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break;
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}
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} else {
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if (operator1 == '/') {
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num2 = random.nextInt(10) + 1; // 避免除零
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}
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correctAnswer = calculate(num1, num2, operator1);
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question = num1 + " " + getOperatorSymbol(operator1) + " " + num2 + " = ?";
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}
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correctAnswer = Double.parseDouble(df.format(correctAnswer));
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String[] options = generateOptions(correctAnswer);
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return new Question(question, options, getCorrectOptionIndex(options, correctAnswer), "小学");
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}
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private Question generateMiddleSchoolQuestion() {
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String question;
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double correctAnswer;
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if (random.nextBoolean()) {
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// 平方或平方根题目
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int num = random.nextInt(20) + 1;
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if (random.nextBoolean()) {
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correctAnswer = Math.pow(num, 2);
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question = num + "² = ?";
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} else {
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int squared = num * num;
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correctAnswer = num;
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question = "√" + squared + " = ?";
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}
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} else {
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// 带加减乘除的题目
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int num1 = random.nextInt(50) + 1;
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int num2 = random.nextInt(50) + 1;
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int num3 = random.nextInt(20) + 1;
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char[] operators = {'+', '-', '*', '/'};
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char operator1 = operators[random.nextInt(operators.length)];
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char operator2 = operators[random.nextInt(operators.length)];
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// 随机组合平方、平方根和基本运算
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if (random.nextBoolean()) {
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// 平方与基本运算组合
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correctAnswer = calculate(Math.pow(num1, 2), num2, operator1);
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question = num1 + "² " + getOperatorSymbol(operator1) + " " + num2 + " = ?";
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} else {
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// 平方根与基本运算组合
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int squared = num3 * num3;
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correctAnswer = calculate(num3, num2, operator1);
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question = "√" + squared + " " + getOperatorSymbol(operator1) + " " + num2 + " = ?";
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}
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}
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correctAnswer = Double.parseDouble(df.format(correctAnswer));
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String[] options = generateOptions(correctAnswer);
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return new Question(question, options, getCorrectOptionIndex(options, correctAnswer), "初中");
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}
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private Question generateHighSchoolQuestion() {
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if (random.nextBoolean()) {
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return HighSchoolQuestionOne();
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} else {
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// 三角函数与基本运算组合
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return HighSchoolQuestionTwo();
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}
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}
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private Question HighSchoolQuestionOne() {
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String question;
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double correctAnswer;
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double angle = random.nextInt(360);
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String[] trigFunctions = {"sin", "cos", "tan"};
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String trigFunction = trigFunctions[random.nextInt(trigFunctions.length)];
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switch (trigFunction) {
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case "sin":
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correctAnswer = Math.sin(Math.toRadians(angle));
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question = "sin(" + angle + "°) = ?";
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break;
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case "cos":
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correctAnswer = Math.cos(Math.toRadians(angle));
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question = "cos(" + angle + "°) = ?";
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break;
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case "tan":
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angle = getSafeTanAngle();
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correctAnswer = Math.tan(Math.toRadians(angle));
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question = "tan(" + angle + "°) = ?";
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break;
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default:
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correctAnswer = 0;
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question = "";
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}
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correctAnswer = Double.parseDouble(df.format(correctAnswer));
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String[] options = generateOptions(correctAnswer);
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return new Question(question, options, getCorrectOptionIndex(options, correctAnswer), "高中");
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}
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private Question HighSchoolQuestionTwo() {
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String question;
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double correctAnswer;
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double angle = random.nextInt(360);
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int num = random.nextInt(20) + 1;
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char[] operators = {'+', '-', '*', '/'};
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char operator = operators[random.nextInt(operators.length)];
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String[] trigFunctions = {"sin", "cos", "tan"};
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String trigFunction = trigFunctions[random.nextInt(trigFunctions.length)];
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double trigValue;
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switch (trigFunction) {
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case "sin":
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trigValue = Math.sin(Math.toRadians(angle));
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question = "sin(" + angle + "°) " + getOperatorSymbol(operator) + " " + num + " = ?";
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break;
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case "cos":
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trigValue = Math.cos(Math.toRadians(angle));
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question = "cos(" + angle + "°) " + getOperatorSymbol(operator) + " " + num + " = ?";
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break;
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case "tan":
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angle = getSafeTanAngle();
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trigValue = Math.tan(Math.toRadians(angle));
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question = "tan(" + angle + "°) " + getOperatorSymbol(operator) + " " + num + " = ?";
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break;
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default:
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trigValue = 0;
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question = "";
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}
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trigValue = Double.parseDouble(df.format(trigValue));
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correctAnswer = calculate(trigValue, num, operator);
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String[] options = generateOptions(correctAnswer);
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return new Question(question, options, getCorrectOptionIndex(options, correctAnswer), "高中");
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}
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// 获取安全的tan角度（更严格的范围）
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private double getSafeTanAngle() {
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// 为tan函数提供更安全的角度范围，避免无限大的值
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// 排除：85°-95°, 265°-275° 等接近90°和270°的角度
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List<Double> safeTanAngles = new ArrayList<>();
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for (int i = 0; i < 360; i++) {
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if (isSafeForTan(i)) {
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safeTanAngles.add((double) i);
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}
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}
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return safeTanAngles.get(random.nextInt(safeTanAngles.size()));
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}
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// 检查角度是否对tan函数安全（更严格的条件）
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private boolean isSafeForTan(double angle) {
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// 排除接近90°、270°的角度，以及排除tan值过大的角度
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return !((angle >= 80 && angle <= 100) ||
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(angle >= 260 && angle <= 280) ||
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(angle >= 170 && angle <= 190) ||
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(angle >= 350 || angle <= 10));
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}
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// 计算方法
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private double calculate(double a, double b, char operator) {
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switch (operator) {
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case '+':
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return a + b;
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case '-':
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return a - b;
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case '*':
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return a * b;
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case '/':
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return b != 0 ? a / b : a; // 避免除零
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default:
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return 0;
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}
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}
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// 获取运算符符号
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private String getOperatorSymbol(char operator) {
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switch (operator) {
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case '+':
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return "+";
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case '-':
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return "-";
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case '*':
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return "×";
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case '/':
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return "÷";
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default:
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return "";
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}
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}
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private String[] generateOptions(double correctAnswer) {
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String[] options = new String[4];
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int correctIndex = random.nextInt(4);
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for (int i = 0; i < 4; i++) {
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if (i == correctIndex) {
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options[i] = df.format(correctAnswer);
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} else {
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double wrongAnswer;
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do {
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double variation = (random.nextDouble() - 0.5) * 10;
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wrongAnswer = correctAnswer + variation;
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wrongAnswer = Double.parseDouble(df.format(wrongAnswer));
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} while (Math.abs(wrongAnswer - correctAnswer) < 0.1);
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options[i] = String.valueOf(wrongAnswer);
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}
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}
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return options;
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}
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private int getCorrectOptionIndex(String[] options, double correctAnswer) {
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for (int i = 0; i < options.length; i++) {
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if (Double.parseDouble(options[i]) == correctAnswer) {
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return i;
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}
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}
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return 0;
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}
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} |
