Use recursion to achieve factorial calculation (20090120)

factorial.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace Factorial
{
    class Program
    {
        public long Factorial(int n)
        {
            if (n == 0 || n == 1)
            {
                return 1;
            }
            else
            {
                return n * Factorial(n - 1);
            }
        }
 
        static void Main(string[] args)
        {
            Program p = new Program();
            long sum = 0;
            for (int i = 1; i < 11; i++)
            {
                sum += p.Factorial(i);
            }
            Console.WriteLine("1! + 2! + ... + 10! = " + sum);
        }
    }
}

problem.md

According to the characteristics of factorial calculation, using recursion to achieve it is very convenient.

Note that recursion is a kind of low efficiency algorithm, especially when calculate with larger operations, so give careful consideration to the circumstances in deciding whether to use it.

This is a example of algorithm I wrote when learning C# programming language.

Example: Calculate 1! + 2! + … + 10! and print out the results. Use recursion to achieve it.