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import java.text.DecimalFormat;
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import java.util.Random;
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public class HighSchoolProblemGenerator extends AbstractProblemGenerator {
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public HighSchoolProblemGenerator(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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double[] operandsVal = new double[operandCount];
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String[] displayOperands = new String[operandCount];
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String[] selectedOperators = new String[operandCount - 1];
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// 生成基本操作数
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for (int i = 0; i < operandCount; i++) {
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int v = random.nextInt(100) + 1;
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operandsVal[i] = v;
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displayOperands[i] = String.valueOf(v);
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}
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// 运算符选择（更均衡，避免连乘/连除）
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String previousOperator = null;
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double pPlus = 0.35, pMinus = 0.25, pTimes = 0.25, pDivide = 0.15;
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for (int i = 0; i < operandCount - 1; i++) {
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String operator;
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if ("*".equals(previousOperator) || "/".equals(previousOperator)) {
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double randValue = random.nextDouble();
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double total = pPlus + pMinus;
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operator = randValue < (pPlus / total) ? "+" : "-";
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} else {
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double randValue = random.nextDouble();
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if (randValue < pPlus) operator = "+";
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else if (randValue < pPlus + pMinus) operator = "-";
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else if (randValue < pPlus + pMinus + pTimes) operator = "*";
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else operator = "/";
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}
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selectedOperators[i] = operator;
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previousOperator = operator;
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}
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// 三角函数
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int trigIndex = random.nextInt(operandCount);
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String[] functions = {"sin", "cos", "tan"};
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String function = functions[random.nextInt(functions.length)];
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int[] angles = {0, 30, 45, 60, 90};
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int angle = angles[random.nextInt(angles.length)];
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if ("tan".equals(function) && angle == 90) angle = 60; // 避免 tan(90°)
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double trigVal = calculateTrigFunction(function, angle);
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operandsVal[trigIndex] = trigVal;
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displayOperands[trigIndex] = function + angle;
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// 括号选择（显示用 displayOperands，计算用 operandsVal）
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boolean addedBracket = false;
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int startPos = findBracketStart(operandsVal, selectedOperators, 0.3);
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StringBuilder expBuilder = new StringBuilder();
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for (int i = 0; i < operandCount; i++) {
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if (startPos != -1 && i == startPos) expBuilder.append("(");
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expBuilder.append(displayOperands[i]);
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if (startPos != -1 && i == startPos + 1) expBuilder.append(")");
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if (i < operandCount - 1) expBuilder.append(" ").append(selectedOperators[i]).append(" ");
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}
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String expression = expBuilder.toString();
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// 计算结果（double）
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double result;
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if (startPos != -1) {
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double bracketResult = applyOperatorDouble(operandsVal[startPos], operandsVal[startPos + 1], selectedOperators[startPos]);
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int newCount = operandCount - 1;
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double[] newVals = new double[newCount];
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String[] newOps = new String[newCount - 1];
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for (int i = 0; i < startPos; i++) newVals[i] = operandsVal[i];
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newVals[startPos] = bracketResult;
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for (int i = startPos + 1; i < newCount; i++) newVals[i] = operandsVal[i + 1];
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for (int i = 0; i < newCount - 1; i++) newOps[i] = (i < startPos) ? selectedOperators[i] : selectedOperators[i + 1];
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result = newVals[0];
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for (int i = 0; i < newCount - 1; i++) result = applyOperatorDouble(result, newVals[i + 1], newOps[i]);
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} else {
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result = operandsVal[0];
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for (int i = 0; i < operandCount - 1; i++) result = applyOperatorDouble(result, operandsVal[i + 1], selectedOperators[i]);
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}
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return new MathProblem(expression, df.format(result), "高中");
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}
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} |
