在这里和Google搜寻了几天,并询问了我的编程朋友.
不幸的是,我仍然不知道如何更改我的代码…
我的程序计算给定数字的阶乘.然后提供一个数字,该数字代表析因答案包含的位数.然后,将这些数字的值相加在一起得出总数.
我的程序适用于1之间的任何数字!和31!…如果您输入超过31! (例如50!或100!),它不起作用,只会返回减号而没有总数.
我希望你们能指出正确的方向或给我一些建议.
我知道使用BigIntegers可能是一种解决方案,但是我个人并不了解它们,因此请来到这里.
任何帮助将非常感激.谢谢.
package java20;
/**
* Program to calculate the factorial of a given number.
* Once implemented, it will calculate how many digits the answer includes.
* It will then sum these digits together to provide a total.
* @author shardy
* date: 30/09/2012
*/
//import java.math.BigInteger;
public class Java20 {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
//Using given number stored in factorialNo, calculates factorial
//currently only works for numbers between 1! and 31! :(
int fact= 1;
int factorialNo = 10;
for (int i = 1; i <= factorialNo; i++)
{
fact=fact*i;
}
System.out.println("The factorial of " + factorialNo +
" (or " + factorialNo + "!) is: " + fact);
//Using answer stored in fact, calculates how many digits the answer has
final int answerNo = fact;
final int digits = 1 + (int)Math.floor(Math.log10(answerNo));
System.out.println("The number of digits in the factorials "
+ "answer is: " + digits);
//Using remainders, calculates each digits value and sums them together
int number = fact;
int reminder;
int sum = 0;
while(number>=1)
{
reminder=number%10;
sum=sum+reminder;
number=number/10;
}
System.out.println("The total sum of all the " + digits
+ " idividual digits from the answer of the factorial of "
+ factorialNo + " is: " + sum);
}
}
解决方法:
您可以在Java中使用BigInteger,它可以根据需要使用任意数量的数字
BigInteger fact= BigInteger.ONE;
int factorialNo = 10;
for (int i = 2; i <= factorialNo; i++){
fact = fact.multiply(new BigInteger(String.valueOf(i)));
}
System.out.println("The factorial of " + factorialNo +
" (or " + factorialNo + "!) is: " + fact);
final int digits = fact.toString().length();
BigInteger number = new BigInteger(fact.toString());
BigInteger reminder;
BigInteger sum = BigInteger.ZERO;
BigInteger ten = new BigInteger(String.valueOf(10));
while(number.compareTo(BigInteger.ONE)>=0)
{
reminder=number.mod(ten);
sum=sum.add(reminder);
number=number.divide(ten);
}
System.out.println("The total sum of all the " + digits
+ " idividual digits from the answer of the factorial of "
+ factorialNo + " is: " + sum
编辑:改进了代码以与作者的代码兼容