Question

I’m solving simple math task, and I have faced with some problems. I have written recursive function, but I don’t get same result as in calculator. For instance n=2,a =2. Can anybody help me?

Task:

1/a + 1/(a+1) +...+ 1/(a(a+1)...(a+n)) 

Here’s my code so far:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace _02__Part_A_
{
    class Program
    {
        float res = 1;

        public float func3(int n, int a)
        {
            if (n == 0)
                return 1 / (a * res);
            res = res * (a + n);
            n--;
            return func3(n, a);
        }

        static void Main(string[] args)
        {
            Program a = new Program();

            float resOFfunc3 = (float)0.5;
            string n = Console.ReadLine();
            string ak = Console.ReadLine();

            for (int nn = int.Parse(n); nn > 0; nn--)
            {
                resOFfunc3 += a.func3(nn, int.Parse(ak));
            }

            Console.WriteLine(resOFfunc3.ToString());
        }

    }
}

Answer 1

you need reset the res variable inside the for loop

namespace _02__Part_A_
{
    class Program
    {

        float res = 1;


        public float func3(int n,int a) {

            if (n == 0)
                return 1/(a*res);
            res = res * (a + n);
            n--;
            return func3(n,a);
        }

        static void Main(string[] args)
        {
            Program a = new Program();

            float resOFfunc3 = (float)0.5;
            string n = Console.ReadLine();
            string ak = Console.ReadLine();
            for (int nn = int.Parse(n); nn > 0; nn--)
            {
                res = 1;   // Need to add this
                resOFfunc3 += a.func3(nn, int.Parse(ak));
            }

            Console.WriteLine(resOFfunc3.ToString());
        }
    }
}