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public class PrimaryQuestionGenerator extends AbstractQuestionGenerator {
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private static final String[] OPERATORS = {"+", "-", "×", "÷"};
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@Override
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public String generateQuestion() {
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int attempts = 0;
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while (attempts < 100) {
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attempts++;
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int operandCount = random.nextInt(4) + 2; // 2~5个操作数
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StringBuilder question = new StringBuilder();
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// 生成操作数和运算符
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for (int i = 0; i < operandCount; i++) {
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question.append(generateNumber());
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if (i < operandCount - 1) {
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question.append(" ").append(generateOperator(OPERATORS)).append(" ");
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}
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}
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// 随机添加括号
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String result = addReasonableParentheses(question.toString(), operandCount);
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result = ensureBalancedParentheses(result); // 确保括号平衡
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if (isQuestionUnique(result) && isValidParentheses(result) && hasOperator(result)) {
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addToGeneratedQuestions(result);
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String regex = "(?<!\\s)\\)(?=[^)]*$)";
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result = result.replaceAll(regex, " )");
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return result;
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}
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}
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return "3 + 5"; // 备用题目
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}
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private String addReasonableParentheses(String expression, int operandCount) {
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if (operandCount <= 2 || random.nextDouble() < 0.3) {
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return expression;
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}
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String[] parts = expression.split(" ");
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if (parts.length < 5) return expression;
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StringBuilder newExpr = new StringBuilder();
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int start = random.nextInt(parts.length / 2);
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int end = start + random.nextInt(parts.length / 2 - start + 1) + 1;
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end = Math.min(end, parts.length / 2 - 1);
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for (int i = 0; i < parts.length; i++) {
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if (i == start * 2) {
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newExpr.append("( ");
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}
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newExpr.append(parts[i]);
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if (i == end * 2 && i >= start * 2 + 2) {
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newExpr.append(" )");
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}
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if (i < parts.length - 1) {
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newExpr.append(" ");
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}
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}
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return newExpr.toString().trim();
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}
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}
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