我的问题是，每当我尝试编译和运行我的程序时，它都会说我接近代码末尾的算术问题之一被零除。现在还有另一个问题。每当提示用户输入掷骰数时，您可以输入一个数字并按 Enter 键，但它只是跳到下一行并且没有任何反应。代码中没有发生任何其他事情。
* 注意*
我无法在此作业中使用数组，因为直到下一部分才会介绍它。
这是我的作业 here 。这就是我应该做的。我不明白这里出了什么问题。我的数学似乎是正确的，但有些地方出了问题。
简而言之，我的作业希望我找到两个 11 面骰子被“滚动”用户输入次数的概率。例如:
如果用户说骰子要掷 100 次，它会输出如下内容 2s:(插入 100 次掷骰后 2 个骰子的总和为 2 的概率) 3s:(插入 100 次掷骰后 2 个骰子的总和为 3 的概率) 4s:(插入 100 次掷骰后 2 个骰子的总和为 4 的概率) 5s:(插入100次掷骰后2个骰子的总和为5的概率)
等等。
这是迄今为止我的代码:
public static void main(String[] args)
{
//Declare and initialize variables and objects
Scanner in = new Scanner(System.in);
Random randNum = new Random();
int match = 0; //Number of times sum of dice matches the current sum
int die1 = 0; //Random generated numbers
int die2 = 0;
int diceTotal2 = 0;
int diceTotal3 = 0;
int diceTotal4 = 0;
int diceTotal5 = 0;
int diceTotal6 = 0;
int diceTotal7 = 0;
int diceTotal8 = 0;
int diceTotal9 = 0;
int diceTotal10 = 0;
int diceTotal11 = 0;
int diceTotal12 = 0;
int sumOfDice = 0;
double probability2 = 0.0;
double probability3 = 0.0;
double probability4 = 0.0;
double probability5 = 0.0;
double probability6 = 0.0;
double probability7 = 0.0;
double probability8 = 0.0;
double probability9 = 0.0;
double probability10 = 0.0;
double probability11 = 0.0;
double probability12 = 0.0;
//Input: ask user for number of rolls and number of sides on a die
System.out.println("Number of Rolls: ");
int rolls = in.nextInt();
//***************************************************************************************
//Using nested loops, cycle through the possible sums of the dice.
//Roll the dice the given number of times for each sum.
//Count how many times the sum of the dice match the current sum being looked for.
//***************************************************************************************
//Loop to increment through the possible sums of the dice
//Loop to throw dice given number of times
for( int numberOfRolls = 1; numberOfRolls < rolls; numberOfRolls++)
{
die1 = randNum.nextInt(6);
die2 = randNum.nextInt(6);
sumOfDice = die1 + die2;
for( ; ; )
{
//Check if the sum of dice is equal to the given sum
if(sumOfDice == 2)
{
diceTotal2++;
probability2 = diceTotal2 / numberOfRolls;
}
else if(sumOfDice ==3)
{
diceTotal3++;
probability3 = diceTotal3 / numberOfRolls;
}
else if(sumOfDice ==4)
{
diceTotal4++;
probability4 = diceTotal4 / numberOfRolls;
}
else if(sumOfDice ==5)
{
diceTotal5++;
probability5 = diceTotal5 / numberOfRolls;
}
else if(sumOfDice ==6)
{
diceTotal6++;
probability6 = diceTotal6 / numberOfRolls;
}
else if(sumOfDice ==7)
{
diceTotal7++;
probability7 = diceTotal7 / numberOfRolls;
}
else if(sumOfDice ==8)
{
diceTotal8++;
probability8 = diceTotal8 / numberOfRolls;
}
else if(sumOfDice ==9)
{
diceTotal9++;
probability9 = diceTotal9 / numberOfRolls;
}
else if(sumOfDice ==10)
{
diceTotal10++;
probability10 = diceTotal10 / numberOfRolls;
}
else if(sumOfDice ==11)
{
diceTotal11++;
probability11 = diceTotal11 / numberOfRolls;
}
else if(sumOfDice ==12)
{
diceTotal12++;
probability12 = diceTotal12 / numberOfRolls;
}
}
}
System.out.println("Sum of Dice" + " " + "Probability");
System.out.println("2s: \t\t" + probability2 + "%");
System.out.println("3s: \t\t" + probability3 + "%");
System.out.println("4s: \t\t" + probability4 + "%");
System.out.println("5s: \t\t" + probability5 + "%");
System.out.println("6s: \t\t" + probability6 + "%");
System.out.println("7s: \t\t" + probability7 + "%");
System.out.println("8s: \t\t" + probability8 + "%");
System.out.println("9s: \t\t" + probability9 + "%");
System.out.println("10s: \t\t" + probability10 + "%");
System.out.println("11s: \t\t" + probability11 + "%");
System.out.println("12s: \t\t" + probability12 + "%");
//After all throws, calculate percentage of throws that resulted in the given sum
} //end main
最佳答案
由于您已经有了一个解决方案，我将向您提供另一个解决方案:
import java.util.Random;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
int nRolls = 100, nDice = 6; // default values
Scanner in = new Scanner(System.in);
System.out.print("Number of throws: ");
nRolls = in.nextInt();
System.out.print("Number of sides on the dices: ");
nDice = in.nextInt();
int minSum = 2, maxSum = 2 * nDice;
int[] hist = new int[maxSum - minSum + 1];
Random rand = new Random();
for (int iter = 1; iter <= nRolls; iter++) {
int throw1 = 1 + rand.nextInt(nDice), throw2 = 1 + rand.nextInt(nDice);
int sum = throw1 + throw2;
hist[sum - minSum]++;
}
System.out.println("Number of rolls: " + nRolls);
System.out.println("Number of sides of the dice: " + nDice);
System.out.println("Sum of Dice Percentage");
for (int i = 0; i < hist.length; i++) {
System.out.println(String.format(" %2d %5.2f%%", i + minSum, hist[i] * 100.0 / nRolls));
// System.out.println(" " + (i+minSum) + " " + (hist[i]*100.0/nRolls);
}
in.close();
}
}
它向您展示了如何使用数组来解决此任务。数组中的每个条目都保存与相应总和相关的抛出次数。您始终有 2*nDice - 1 可能的总和(您无法用两个骰子达到 1)，因此数组的大小取决于骰子上的边数骰子。
然后你只需迭代所有抛出，并将 1 添加到相应的直方图条目(请注意，我偏移了直方图，因此 hist[0] 对应于 2 的总和，hist[ 1] 总和为 3，等等)。
最后，您可以计算百分比。 (这不是概率，而是在我们的模拟中该总和发生的百分比。如果您将掷骰数设置得更大，则该百分比将是概率的近似值。)
最后，您只需将其打印出来即可。 String.format 内容仅用于值的对齐。如果你对此感到困惑，只需使用
System.out.println(" " + (i+minSum) + " " + (hist[i]*100.0/nRolls);
相反。
关于java - 在 Java 中使用嵌套 for 循环查找概率，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12897848/