一个数的阶乘的Java程序

非负整数的阶乘，是所有小于或等于 n 的整数的乘积。例如，6 的阶乘是 6*5*4*3*2*1，即 720。

递归：

// Java program to find factorial of given number
class Test
{
    // method to find factorial of given number
    static int factorial(int n)
    {
        if (n == 0)
          return 1;
          
        return n*factorial(n-1);
    }
      
    // Driver method
    public static void main(String[] args) 
    {
        int num = 5;
        System.out.println("Factorial of "+ num + " is " + factorial(5));
    }
}

迭代解决方案：

// Java program to find factorial of given number
class Test
{
    // Method to find factorial of given number
    static int factorial(int n)
    {
        int res = 1, i;
        for (i=2; i<=n; i++)
            res *= i;
        return res;
    }
      
    // Driver method
    public static void main(String[] args) 
    {
        int num = 5;
        System.out.println("Factorial of "+ num + " is " + factorial(5));
    }
}

一条线解决方案（使用三元运算符）：

// Java program to find factorial
// of given number
class Factorial {
  
  int factorial(int n)
  {
  
    // single line to find factorial
    return (n == 1 || n == 0) ? 1 : n * factorial(n - 1);
  
  }
  
  
  // Driver Code
  public static void main(String args[])     
  {
    Factorial obj = new Factorial();
    int num = 5;
    System.out.println("Factorial of " + num + 
                      " is " + obj.factorial(num));
   }
}
// This code is contributed by Anshika Goyal.

上述解决方案会导致小数溢出。请参考大数阶乘以获得适用于大数的解决方案。

有关更多详细信息，请参阅有关数字阶乘的完整文章！