小学生100以内的四则运算-Java

ゝ一纸荒年。 2022-05-29 13:51 135阅读 0赞

*  要求  
    ![这里写图片描述][70]
 *  实现

package cn.com.hellowood.spider;
    
    import javax.script.ScriptEngine;
    import javax.script.ScriptEngineManager;
    import javax.script.ScriptException;
    import java.io.File;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Random;
    import java.util.Scanner;
    
    /** * 生成100以内四则运算 * <p> * 要求： * 1. 0-100之间的四则运算 * 2. 3-5个运算符 * 3. 运算过程中不允许出现负数和分数 * 4. 系统输入生成的题数量 * 5. 输出到 result.txt 文件中，文件目录为当前classpath * 6. 文件首行输出学号 * <p> * 使用穷举随机生成题目，会造成大量的栈内存使用，当生成的问题比较多时有可能失败， * 可以考虑根据规则反向拼接生成 */
    public class CalculateGenerator { 
    
        private static ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName("JavaScript");
    
        private static final char PLUS = '+';
        private static final char MINUS = '-';
        private static final char MULTIPLY = '*';
        private static final char DIVIDE = '/';
        private static final char DISPLAY_DIVIDE = '÷';
        private static final char EQUALS = '=';
        private static final String DOT = ".";
        private static final String DOT_REGEX = "\\.";
    
        private static final char[] operators = {PLUS, MINUS, MULTIPLY, DIVIDE};
        private static final Integer MIN_OPERATOR_COUNT = 3;
        private static final Integer MAX_OPERATOR_COUNT = 5;
        private static final Integer MIN_CAL_VALUE = 0;
        private static final Integer MAX_CAL_VALUE = 100;
    
        private static final String FILE_NAME = "result.txt";
        private static final String STUDENT_NO = "STUDENT_NO";
        private static final String NEW_LINE = "\r\n";
    
        private static Random random = new Random();
    
    
        public static void main(String[] args) throws ScriptException {
            System.out.println("请输入要生成的练习题数量：");
            Scanner scanner = new Scanner(System.in);
    
            Integer expressionCount = scanner.nextInt();
    
            List<String> expressionList = new ArrayList<>();
            for (int i = 0; i < expressionCount; i++) {
                expressionList.add(getNextExpression());
                System.out.println(String.format("正在生成第 %s 道题", i));
            }
    
            writeExpressionsToFile(expressionList);
            System.out.println("生成练习题完成");
        }
    
        /** * 将练习题输出到文件 * * @param expressionList */
        private static void writeExpressionsToFile(List<String> expressionList) {
            File file = new File(FILE_NAME);
            try (FileWriter fileWriter = new FileWriter(file)) {
                fileWriter.append(STUDENT_NO);
                for (String expression : expressionList) {
                    fileWriter.append(NEW_LINE);
                    fileWriter.append(expression);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    
        /** * 生成练习题 * * @return * @throws ScriptException */
        private static String getNextExpression() throws ScriptException {
            System.out.println("尝试生成下一道题");
    
            // 运算符数量
            int operatorCount = random.nextInt(MAX_OPERATOR_COUNT + 1 - MIN_OPERATOR_COUNT) + MIN_OPERATOR_COUNT;
    
            StringBuilder expression = new StringBuilder();
    
            // 运算符
            List<Character> operatorList = getOperatorList(operatorCount);
    
            // 运算数
            List<Integer> calValueList = getCalValueList(operatorCount + 1);
    
            for (int i = 0; i < operatorList.size(); i++) {
                Character operator = operatorList.get(i);
    
                Integer previousCalValue = calValueList.get(i);
                Integer nextCalValue = calValueList.get(i + 1);
                expression.append(previousCalValue);
    
                // 除法校验除数不为0且能被整除
                if (DIVIDE == operator) {
                    calValueList.set(i + 1, getDivideCalValue(previousCalValue, nextCalValue));
                } else if (MINUS == operator) {
                    // 减法校验被减数大于减数
                    // 当包含小数点时向下取整
                    String currentResultString = scriptEngine.eval(expression.toString()).toString();
                    if (currentResultString.contains(DOT)) {
                        currentResultString = currentResultString.split(DOT_REGEX)[0];
                    }
                    Integer currentResult = Integer.valueOf(currentResultString);
                    while (currentResult < nextCalValue) {
                        nextCalValue = random.nextInt(MAX_CAL_VALUE + 1);
                    }
                    calValueList.set(i + 1, nextCalValue);
                }
    
                expression.append(operator);
            }
    
            expression.append(calValueList.get(operatorCount));
    
            // 计算当前结果是否为正整数
            String result = scriptEngine.eval(expression.toString()).toString();
    
            if (result.contains(DOT) || Integer.valueOf(result) < 0) {
                System.out.println("当前题目不符合要求");
                return getNextExpression();
            }
    
            String currentExpression = expression.append(EQUALS).append(result)
                    .toString()
                    .replaceAll(String.valueOf(DIVIDE), String.valueOf(DISPLAY_DIVIDE));
            return currentExpression;
        }
    
        /** * 获取运算符 * * @param operatorCount * @return */
        private static List<Character> getOperatorList(int operatorCount) {
            List<Character> operatorList = new ArrayList<>();
            for (int i = 0; i < operatorCount; i++) {
                Character operator = operators[random.nextInt(operators.length)];
                operatorList.add(operator);
            }
            return operatorList;
        }
    
        /** * 获取运算数 * * @param calValueCount * @return */
        private static List<Integer> getCalValueList(int calValueCount) {
            List<Integer> calValueList = new ArrayList<>();
            for (int i = 0; i < calValueCount; i++) {
                calValueList.add(random.nextInt(MAX_CAL_VALUE + 1));
            }
            return calValueList;
        }
    
        /** * 当为除法时校验除数不为0且能被整除 * * @param previousCalValue * @param nextCalValue * @return */
        private static int getDivideCalValue(Integer previousCalValue, Integer nextCalValue) {
            if (nextCalValue == 0 || previousCalValue % nextCalValue != 0) {
                nextCalValue = random.nextInt(MAX_CAL_VALUE) + 1;
                return getDivideCalValue(previousCalValue, nextCalValue);
            }
            return nextCalValue;
        }
    }

[70]: /images/20220529/0b9d86088610401d999cfa42671c829a.png