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import java.text.DecimalFormat;
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import java.util.Random;
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public class MiddleSchoolProblemGenerator extends AbstractProblemGenerator {
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public MiddleSchoolProblemGenerator(Random random, DecimalFormat df) {
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super(random, df);
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}
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@Override
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public MathProblem generate() {
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int operandCount = random.nextInt(3) + 3; // 3-5 个操作数
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int[] operands = new int[operandCount];
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String[] selectedOperators = new String[operandCount - 1];
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String[] displayOperands = new String[operandCount];
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String[] operatorPool = {"+", "-", "*", "/"};
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for (int i = 0; i < operandCount; i++) {
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operands[i] = random.nextInt(100) + 1;
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displayOperands[i] = String.valueOf(operands[i]);
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}
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for (int i = 0; i < operandCount - 1; i++) {
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selectedOperators[i] = operatorPool[random.nextInt(operatorPool.length)];
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}
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// 平方或根号
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int specialOperandIndex = random.nextInt(operandCount);
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boolean useSquareRoot = random.nextBoolean();
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if (useSquareRoot) {
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int base = random.nextInt(24) + 2; //2-25
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int perfectSquare = base * base;
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operands[specialOperandIndex] = base; // √(base^2) = base
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displayOperands[specialOperandIndex] = "√" + perfectSquare;
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} else {
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int base = random.nextInt(9) + 2; // 2-10
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int square = base * base;
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operands[specialOperandIndex] = square;
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displayOperands[specialOperandIndex] = base + "²";
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}
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// 括号选择
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boolean addedBracket = false;
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int bracketStartIndex = findBracketStart(toDoubleArray(operands), selectedOperators, 0.3);
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String expression;
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double result;
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if (bracketStartIndex != -1) {
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// 构建带括号（显示用 displayOperands）
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StringBuilder expressionBuilder = new StringBuilder();
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for (int i = 0; i < operandCount; i++) {
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if (i == bracketStartIndex) expressionBuilder.append("(");
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expressionBuilder.append(displayOperands[i]);
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if (i == bracketStartIndex + 1) expressionBuilder.append(")");
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if (i < operandCount - 1) expressionBuilder.append(" ").append(selectedOperators[i]).append(" ");
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}
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expression = expressionBuilder.toString();
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result = evaluateExpressionWithBrackets(operands, selectedOperators, bracketStartIndex);
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} else {
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StringBuilder expressionBuilder = new StringBuilder();
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expressionBuilder.append(displayOperands[0]);
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result = operands[0];
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for (int i = 0; i < operandCount - 1; i++) {
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expressionBuilder.append(" ").append(selectedOperators[i]).append(" ").append(displayOperands[i + 1]);
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result = applyOperator(result, operands[i + 1], selectedOperators[i]);
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}
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expression = expressionBuilder.toString();
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}
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return new MathProblem(expression, df.format(result), "初中");
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}
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} |
