随机生成方程和答案

Question

我正在尝试随机生成一个方程式，该方程式也有 50% 的几率出错并显示不正确的答案。错误答案应该有 -2、-1、+1 或 +2 的错误。

有时我的代码会打印这样的除法方程（我不能 post 图片）： 2 / 10 = 13 1 / 5 = 43 等等

我不明白为什么方程显示混合的数字，但没有一起检查？

（首先在我的 onCreateView 方法

中调用 generateNumbers()

public void generateNumbers() {
    //randomly generate 2 numbers and an operator
    number1 = (int) (Math.random() * 10) + 1;
    number2 = (int) (Math.random() * 10) + 1;
    operator = (int) (Math.random() * 4) + 1;
    //50% chance whether the displayed answer will be right or wrong
    rightOrWrong = (int) (Math.random() * 2) + 1;
    //calculate the offset of displayed answer for a wrong equation (Error)
    error = (int) (Math.random() * 4) + 1;
    generateEquation();
}

public void generateEquation() {
    StringBuilder equation = new StringBuilder();
    //append the first number
    equation.append(number1);
    //generate/append the operator and calculate the real answer
    if (operator == 1) {
        equation.append(" + ");
        actualAnswer = number1 + number2;
    } else if (operator == 2) {
        equation.append(" - ");
        actualAnswer = number1 - number2;
    } else if (operator == 3) {
        equation.append(" x ");
        actualAnswer = number1 * number2;
    } else if (operator == 4) {
        if ((number1%number2==0) && (number1>number2)) {
            actualAnswer = number1 / number2;
        } else {
            generateNumbers();
        }
        equation.append(" / ");

    }
    //append the second number and the equals sign
    equation.append(number2 + " = ");

    //we will display the correct answer for the equation
    if (rightOrWrong == 1) {
        displayedAnswer = actualAnswer;
        equation.append(displayedAnswer);
    }
    //we will display an incorrect answer for the equation
    //need to calculate error (-2, -1, +1, +2)
    else {
        if (error == 1) {
            displayedAnswer = actualAnswer - 1;
        } else if (error == 2) {
            displayedAnswer = actualAnswer - 2;
        }else if (error == 3) {
            displayedAnswer = actualAnswer + 1;
        }else {
            displayedAnswer = actualAnswer + 2;
        }
        //append the displayed answer with error
        equation.append(displayedAnswer);

    }
    questionNumber.setText("You have answered " + count + " out of 20 questions");
    finalEquation.setText(equation.toString());
}

Answer 1

我认为您需要在

中调用 generateNumbers 之后放置一个 return 语句

} else if (operator == 4) {
    if ((number1%number2==0) && (number1>number2)) {
        actualAnswer = number1 / number2;
    } else {
        generateNumbers();
    }
    equation.append(" / ");

}

因为这将重新启动整个过程，而不是继续使用更多数字。

Answer 2

更改您的代码以解决低概率除法问题：

public void generateNumbers() {
    number1 = (int) (Math.random() * 10) + 1;
    number2 = (int) (Math.random() * 10) + 1;

    //don't get operator here
    //operator = (int) (Math.random() * 4) + 1;

    rightOrWrong = (int) (Math.random() * 2) + 1;
    error = (int) (Math.random() * 4) + 1;

    //don't generate equation here, start (in the View with generateEquation instead of generate numbers
    //generateEquation();
}

public void generateEquation() {
    StringBuilder equation = new StringBuilder();
    generateNumbers();

    //determine operator here
    operator = (int) (Math.random() * 4) + 1;


    equation.append(number1);
    if (operator == 1) {
        equation.append(" + ");
        actualAnswer = number1 + number2;
    } else if (operator == 2) {
        equation.append(" - ");
        actualAnswer = number1 - number2;
    } else if (operator == 3) {
        equation.append(" x ");
        actualAnswer = number1 * number2;
    } else if (operator == 4) {
        equation.append(" / ");
        // generate new numbers if they are not suiteable
        while((number1%number2!=0) && (number1<number2))
        {
            generateNumbers();
        }
        actualAnswer = number1 / number2;
    }
    ......

随机生成方程和答案

Randomly generating equation and answer

java

random

android

equation