java - 计算 10 .. 100 的阶乘而不重复任何代码？

Question

我可以通过使用 for 循环来做到这一点，但它太长了。我必须执行大约 10 个 for 循环。

 System.out.println("factorial of 10");
 int fact = 1;
 for (int x=1;x<=10;x++) {
     fact=fact*x;
     System.out.println(fact);
 }

 System.out.println(" factorial of 20 ");
 double fact1 = 1;
 for (double y=1;y<=20;y++){
     fact1=fact1*y;
     System.out.println(fact1);
 }

Answer 1

您可以使用递归方法来计算阶乘。还可以根据您在解决方案中调整类型。例如 BigInteger 或 Long

public class Factorial {
    public static void main (String[] args) {
        int theNum, theFact;
        System.out.println("This program computes the factorial " +
                "of a number.");
        System.out.print("Enter a number: ");
        theNum=Console.in.readInt();
        theFact = fact(theNum);
        System.out.println(theNum + "! = " + theFact + ".");
    }

    static int fact(int n) {
        if (n <= 1) {
            return 1;
        }
        else {
            return n * fact(n-1);
        }
    }
}