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package service.generator;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.Random;
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public abstract class AbstractQuestionGenerator implements QuestionGenerator {
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protected final Random rand = new Random();
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private static final char[] OPS = {'+', '-', '×', '÷'};
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protected String buildComplexExpression(List<String> operands) {
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int numOperands = operands.size();
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if (numOperands < 2) return operands.get(0); // 如果只有一个操作数，直接返回
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List<Character> operators = new ArrayList<>();
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for (int i = 0; i < numOperands - 1; i++) {
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operators.add(OPS[rand.nextInt(OPS.length)]);
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}
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int parensType = rand.nextInt(5); // 增加不加括号的概率
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switch (parensType) {
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case 1: // 单括号 (a op b) op c ...
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if (numOperands >= 3) {
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Collections.swap(operands, 0, rand.nextInt(numOperands));
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Collections.swap(operands, 1, rand.nextInt(numOperands));
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return String.format("(%s %c %s) %c %s", operands.get(0), operators.get(0), operands.get(1), operators.get(1), buildRest(operands, operators, 2));
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}
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break;
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case 2: // a op (b op c) op d ...
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if (numOperands >= 3) {
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return String.format("%s %c (%s %c %s)", operands.get(0), operators.get(0), operands.get(1), operators.get(1), buildRest(operands, operators, 2));
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}
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break;
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case 3: // 双重括号 ((a op b) op c) op d ...
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if (numOperands >= 4) {
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return String.format("((%s %c %s) %c %s) %c %s", operands.get(0), operators.get(0), operands.get(1), operators.get(1), operands.get(2), operators.get(2), buildRest(operands, operators, 3));
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}
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break;
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case 4: // 双重括号 a op (b op (c op d)) ...
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if (numOperands >= 4) {
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return String.format("%s %c (%s %c (%s %c %s))", operands.get(0), operators.get(0), operands.get(1), operators.get(1), operands.get(2), operators.get(2), buildRest(operands, operators, 3));
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}
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break;
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}
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// 默认情况：无括号或无法应用括号
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return buildRest(operands, operators, 0);
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}
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private String buildRest(List<String> operands, List<Character> operators, int startIndex) {
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StringBuilder sb = new StringBuilder();
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sb.append(operands.get(startIndex));
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for (int i = startIndex; i < operators.size(); i++) {
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sb.append(" ").append(operators.get(i)).append(" ");
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sb.append(operands.get(i + 1));
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}
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return sb.toString();
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}
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} |
