四则运算

import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
import java.util.Timer;
import java.util.TimerTask;

class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
Random random = new Random();

    System.out.println("请输入要做的题目总数：");
    int totalQuestions = scanner.nextInt();

    // 用户输入各种运算类型的题目数量
    System.out.println("请输入加法题数量：");
    int addQuestionCount = scanner.nextInt();

    System.out.println("请输入减法题数量：");
    int subtractQuestionCount = scanner.nextInt();

    System.out.println("请输入乘法题数量：");
    int multiplyQuestionCount = scanner.nextInt();

    System.out.println("请输入除法题数量：");
    int divideQuestionCount = scanner.nextInt();

    int sumOfUserSpecified = addQuestionCount + subtractQuestionCount + multiplyQuestionCount + divideQuestionCount;

    if (sumOfUserSpecified < totalQuestions) {
        int remaining = totalQuestions - sumOfUserSpecified;
        while (remaining > 0) {
            int randomOp = random.nextInt(4);
            switch (randomOp) {
                case 0:
                    addQuestionCount++;
                    break;
                case 1:
                    subtractQuestionCount++;
                    break;
                case 2:
                    multiplyQuestionCount++;
                    break;
                case 3:
                    divideQuestionCount++;
                    break;
            }
            remaining--;
        }
    } else if (sumOfUserSpecified > totalQuestions) {
        List<Integer> opCounts = new ArrayList<>();
        opCounts.add(addQuestionCount);
        opCounts.add(subtractQuestionCount);
        opCounts.add(multiplyQuestionCount);
        opCounts.add(divideQuestionCount);
        while (sumOfUserSpecified > totalQuestions) {
            int randomIndex = random.nextInt(4);
            if (opCounts.get(randomIndex) > 0) {
                opCounts.set(randomIndex, opCounts.get(randomIndex) - 1);
                sumOfUserSpecified--;
            }
        }
        addQuestionCount = opCounts.get(0);
        subtractQuestionCount = opCounts.get(1);
        multiplyQuestionCount = opCounts.get(2);
        divideQuestionCount = opCounts.get(3);
    }

    // 设置倒计时两分钟（120000 毫秒）
    Timer timer = new Timer();
    timer.schedule(new TimerTask() {
        @Override
        public void run() {
            System.out.println("\n时间到！");
            System.exit(0);
        }
    }, 120000);

    int correctCount = 0;
    int wrongCount = 0;
    int questionNumber = 0;

    List<Question> wrongQuestions = new ArrayList<>();

    while (questionNumber < totalQuestions) {
        BigDecimal n1 = null;
        BigDecimal n2 = null;
        BigDecimal expectedResult = null;
        String op = "";

        if (addQuestionCount > 0) {
            if (random.nextBoolean()) {
                n1 = BigDecimal.valueOf(random.nextInt(1000));
                n2 = BigDecimal.valueOf(random.nextInt(1000));
            } else {
                n1 = BigDecimal.valueOf(random.nextDouble() * 1000);
                n2 = BigDecimal.valueOf(random.nextDouble() * 1000);
            }
            op = "+";
            expectedResult = BigNumberCalculator.add(n1, n2);
            addQuestionCount--;
        } else if (subtractQuestionCount > 0) {
            if (random.nextBoolean()) {
                n1 = BigDecimal.valueOf(random.nextInt(1000));
                n2 = BigDecimal.valueOf(random.nextInt(1000));
                if (n1.compareTo(n2) < 0) {
                    BigDecimal temp = n1;
                    n1 = n2;
                    n2 = temp;
                }
            } else {
                n1 = BigDecimal.valueOf(random.nextDouble() * 1000);
                n2 = BigDecimal.valueOf(random.nextDouble() * 1000);
                if (n1.compareTo(n2) < 0) {
                    BigDecimal temp = n1;
                    n1 = n2;
                    n2 = temp;
                }
            }
            op = "-";
            expectedResult = BigNumberCalculator.subtract(n1, n2);
            subtractQuestionCount--;
        } else if (multiplyQuestionCount > 0) {
            if (random.nextBoolean()) {
                n1 = BigDecimal.valueOf(random.nextInt(100));
                n2 = BigDecimal.valueOf(random.nextInt(100));
            } else {
                n1 = BigDecimal.valueOf(random.nextDouble() * 100);
                n2 = BigDecimal.valueOf(random.nextDouble() * 100);
            }
            op = "*";
            expectedResult = BigNumberCalculator.multiply(n1, n2);
            multiplyQuestionCount--;
        } else if (divideQuestionCount > 0) {
            if (random.nextBoolean()) {
                n1 = BigDecimal.valueOf(random.nextInt(1000));
                n2 = BigDecimal.valueOf(random.nextInt(100));
                if (n2.compareTo(BigDecimal.ZERO) == 0) {
                    n2 = BigDecimal.ONE;
                }
            } else {
                n1 = BigDecimal.valueOf(random.nextDouble() * 1000);
                n2 = BigDecimal.valueOf(random.nextDouble() * 100);
                if (n2.compareTo(BigDecimal.ZERO) == 0) {
                    n2 = BigDecimal.ONE;
                }
            }
            op = "/";
            expectedResult = BigNumberCalculator.divide(n1, n2);
            divideQuestionCount--;
        }

        DecimalFormat df = new DecimalFormat("0.00");
        System.out.println(df.format(n1) + " " + op + " " + df.format(n2) + " =");
        while (!scanner.hasNextBigDecimal()) {
            System.out.println("请输入浮点数或大数答案:");
            scanner.next();
        }
        BigDecimal userAnswer = scanner.nextBigDecimal();

        if (userAnswer.compareTo(expectedResult) == 0) {
            System.out.println("正确！");
            correctCount++;
            questionNumber++;
        } else {
            System.out.println("错误！正确答案是：" + df.format(expectedResult));
            wrongCount++;
            questionNumber++;
            wrongQuestions.add(new Question(df.format(n1), op, df.format(n2), expectedResult, userAnswer));
        }
    }

    timer.cancel();

    System.out.println("错题数：" + wrongCount);
    double accuracy = (correctCount / (double) totalQuestions) * 100;

    // 使用 DecimalFormat 格式化输出结果，保留两位小数
    DecimalFormat dfAccuracy = new DecimalFormat("0.00");
    System.out.println("正确率：" + dfAccuracy.format(accuracy) + "%");

    boolean continueTesting = true;
    while (continueTesting) {
        System.out.println("\n是否进行下一套题目答题？(y/n)");
        String nextChoice = scanner.next();
        if (nextChoice.equalsIgnoreCase("y")) {
            // 重置计数器和题目数量
            correctCount = 0;
            wrongCount = 0;
            questionNumber = 0;
            wrongQuestions.clear();

            System.out.println("请输入要做的题目总数：");
            totalQuestions = scanner.nextInt();

            System.out.println("请输入加法题数量：");
            addQuestionCount = scanner.nextInt();

            System.out.println("请输入减法题数量：");
            subtractQuestionCount = scanner.nextInt();

            System.out.println("请输入乘法题数量：");
            multiplyQuestionCount = scanner.nextInt();

            System.out.println("请输入除法题数量：");
            divideQuestionCount = scanner.nextInt();

            sumOfUserSpecified = addQuestionCount + subtractQuestionCount + multiplyQuestionCount + divideQuestionCount;

            if (sumOfUserSpecified < totalQuestions) {
                int remaining = totalQuestions - sumOfUserSpecified;
                while (remaining > 0) {
                    int randomOp = random.nextInt(4);
                    switch (randomOp) {
                        case 0:
                            addQuestionCount++;
                            break;
                        case 1:
                            subtractQuestionCount++;
                            break;
                        case 2:
                            multiplyQuestionCount++;
                            break;
                        case 3:
                            divideQuestionCount++;
                            break;
                    }
                    remaining--;
                }
            } else if (sumOfUserSpecified > totalQuestions) {
                List<Integer> opCounts = new ArrayList<>();
                opCounts.add(addQuestionCount);
                opCounts.add(subtractQuestionCount);
                opCounts.add(multiplyQuestionCount);
                opCounts.add(divideQuestionCount);
                while (sumOfUserSpecified > totalQuestions) {
                    int randomIndex = random.nextInt(4);
                    if (opCounts.get(randomIndex) > 0) {
                        opCounts.set(randomIndex, opCounts.get(randomIndex) - 1);
                        sumOfUserSpecified--;
                    }
                }
                addQuestionCount = opCounts.get(0);
                subtractQuestionCount = opCounts.get(1);
                multiplyQuestionCount = opCounts.get(2);
                divideQuestionCount = opCounts.get(3);
            }

            // 重新开始答题循环
            while (questionNumber < totalQuestions) {
                BigDecimal n1New = null;
                BigDecimal n2New = null;
                BigDecimal expectedResultNew = null;
                String opNew = "";

                if (addQuestionCount > 0) {
                    if (random.nextBoolean()) {
                        n1New = BigDecimal.valueOf(random.nextInt(1000));
                        n2New = BigDecimal.valueOf(random.nextInt(1000));
                    } else {
                        n1New = BigDecimal.valueOf(random.nextDouble() * 1000);
                        n2New = BigDecimal.valueOf(random.nextDouble() * 1000);
                    }
                    opNew = "+";
                    expectedResultNew = BigNumberCalculator.add(n1New, n2New);
                    addQuestionCount--;
                } else if (subtractQuestionCount > 0) {
                    if (random.nextBoolean()) {
                        n1New = BigDecimal.valueOf(random.nextInt(1000));
                        n2New = BigDecimal.valueOf(random.nextInt(1000));
                        if (n1New.compareTo(n2New) < 0) {
                            BigDecimal temp = n1New;
                            n1New = n2New;
                            n2New = temp;
                        }
                    } else {
                        n1New = BigDecimal.valueOf(random.nextDouble() * 1000);
                        n2New = BigDecimal.valueOf(random.nextDouble() * 1000);
                        if (n1New.compareTo(n2New) < 0) {
                            BigDecimal temp = n1New;
                            n1New = n2New;
                            n2New = temp;
                        }
                    }
                    opNew = "-";
                    expectedResultNew = BigNumberCalculator.subtract(n1New, n2New);
                    subtractQuestionCount--;
                } else if (multiplyQuestionCount > 0) {
                    if (random.nextBoolean()) {
                        n1New = BigDecimal.valueOf(random.nextInt(100));
                        n2New = BigDecimal.valueOf(random.nextInt(100));
                    } else {
                        n1New = BigDecimal.valueOf(random.nextDouble() * 100);
                        n2New = BigDecimal.valueOf(random.nextDouble() * 100);
                    }
                    opNew = "*";
                    expectedResultNew = BigNumberCalculator.multiply(n1New, n2New);
                    multiplyQuestionCount--;
                } else if (divideQuestionCount > 0) {
                    if (random.nextBoolean()) {
                        n1New = BigDecimal.valueOf(random.nextInt(1000));
                        n2New = BigDecimal.valueOf(random.nextInt(100));
                        if (n2New.compareTo(BigDecimal.ZERO) == 0) {
                            n2New = BigDecimal.ONE;
                        }
                    } else {
                        n1New = BigDecimal.valueOf(random.nextDouble() * 1000);
                        n2New = BigDecimal.valueOf(random.nextDouble() * 100);
                        if (n2New.compareTo(BigDecimal.ZERO) == 0) {
                            n2New = BigDecimal.ONE;
                        }
                    }
                    opNew = "/";
                    expectedResultNew = BigNumberCalculator.divide(n1New, n2New);
                    divideQuestionCount--;
                }

                DecimalFormat dfNew = new DecimalFormat("0.00");
                System.out.println(dfNew.format(n1New) + " " + opNew + " " + dfNew.format(n2New) + " =");
                while (!scanner.hasNextBigDecimal()) {
                    System.out.println("请输入浮点数或大数答案:");
                    scanner.next();
                }
                BigDecimal userAnswerNew = scanner.nextBigDecimal();

                if (userAnswerNew.compareTo(expectedResultNew) == 0) {
                    System.out.println("正确！");
                    correctCount++;
                    questionNumber++;
                } else {
                    System.out.println("错误！正确答案是：" + dfNew.format(expectedResultNew));
                    wrongCount++;
                    questionNumber++;
                    wrongQuestions.add(new Question(dfNew.format(n1New), opNew, dfNew.format(n2New), expectedResultNew, userAnswerNew));
                }
            }

            timer.cancel();

            System.out.println("错题数：" + wrongCount);
            accuracy = (correctCount / (double) totalQuestions) * 100;

            // 使用 DecimalFormat 格式化输出结果，保留两位小数
            dfAccuracy = new DecimalFormat("0.00");
            System.out.println("正确率：" + dfAccuracy.format(accuracy) + "%");
        } else {
            continueTesting = false;
        }
    }

    // 错题集功能
    if (!wrongQuestions.isEmpty()) {
        System.out.println("\n错题集：");
        for (Question question : wrongQuestions) {
            System.out.println(question.n1 + " " + question.op + " " + question.n2 + " = (你的答案：" + question.userAnswer + ", 正确答案：" + question.expectedAnswer + ")");
        }
    }

    // 错题重练功能
    System.out.println("\n是否进行错题重练？(y/n)");
    String choice = scanner.next();
    if (choice.equalsIgnoreCase("y")) {
        int retryCorrectCount = 0;
        int retryWrongCount = 0;
        for (Question question : wrongQuestions) {
            System.out.println(question.n1 + " " + question.op + " " + question.n2 + " =");
            while (!scanner.hasNextBigDecimal()) {
                System.out.println("请输入浮点数或大数答案:");
                scanner.next();
            }
            BigDecimal retryUserAnswer = scanner.nextBigDecimal();
            if (retryUserAnswer.compareTo(question.expectedAnswer) == 0) {
                System.out.println("正确！");
                retryCorrectCount++;
            } else {
                System.out.println("错误！正确答案是：" + question.expectedAnswer);
                retryWrongCount++;
            }
        }
        System.out.println("错题重练结果：正确 " + retryCorrectCount + " 题，错误 " + retryWrongCount + " 题。");
    }
}

}

class BigNumberCalculator {
public static BigDecimal add(BigDecimal num1, BigDecimal num2) {
return num1.add(num2);
}

public static BigDecimal subtract(BigDecimal num1, BigDecimal num2) {
    return num1.subtract(num2);
}

public static BigDecimal multiply(BigDecimal num1, BigDecimal num2) {
    return num1.multiply(num2);
}

public static BigDecimal divide(BigDecimal num1, BigDecimal num2) {
    if (num2.compareTo(BigDecimal.ZERO) == 0) {
        throw new ArithmeticException("除数不能为零");
    }
    return num1.divide(num2, 2, BigDecimal.ROUND_HALF_UP);
}

}

class Question {
String n1;
String op;
String n2;
BigDecimal expectedAnswer;
BigDecimal userAnswer;

public Question(String n1, String op, String n2, BigDecimal expectedAnswer, BigDecimal userAnswer) {
    this.n1 = n1;
    this.op = op;
    this.n2 = n2;
    this.expectedAnswer = expectedAnswer;
    this.userAnswer = userAnswer;
}

}