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31 lines
972 B
31 lines
972 B
package com.personalproject.generator;
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import java.util.Random;
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/**
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* 生成包含基础四则运算的小学难度题目表达式.
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*/
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public final class PrimaryQuestionGenerator implements QuestionGenerator {
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private static final String[] OPERATORS = {"+", "-", "*", "/"};
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@Override
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public String generateQuestion(Random random) {
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// 至少生成两个操作数，避免题目退化成单个数字
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int operandCount = random.nextInt(4) + 2;
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StringBuilder builder = new StringBuilder();
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for (int index = 0; index < operandCount; index++) {
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if (index > 0) {
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String operator = OPERATORS[random.nextInt(OPERATORS.length)];
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builder.append(' ').append(operator).append(' ');
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}
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int value = random.nextInt(100) + 1;
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builder.append(value);
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}
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String expression = builder.toString();
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if (operandCount > 1 && random.nextBoolean()) {
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return '(' + expression + ')';
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}
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return expression;
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}
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}
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