Please Help Recursive Math

[ND04]

I Had This Homework About The Recursive Math, But My Professor Gave Us Very Vague Lecture Information.

This First Recursive Program:

#include <iostream>
using namespace std;
int f (int n)
{
	if (n == 5)
	{
		return 0;
	}
	else
	{
		return n * n * n + f (n-1);
	}
}
int main()
{
	cout<<"1^3 + 2^3 + 3^3 + ... + n^3 = \n"<<endl;
	cout<<f(20)<<"\n"<<endl;

	system("pause");
	return 0;
}

Is Calling Statement Of n=50;
Which Mean The Increment By 1, Starting From

2^3 + 3^3 + 4^3+ ... + n^3 and for n = 50

But Base On This Program, My Professor Also Want To Have Similar Recursive, This Time, Instead Of The Increment Of The n Integers. He Want The Program To Be Written Something Like This:

8^2 + 8^3 + 8^4 + ... + 8^n and for n = 30

I Really Lost From Here.
Could Somebody Give Me Some Hint / Helps Base On Program 1 And Applies The Concepts Into The Program 2, Please?

Much Appreciate And Thanks In Advanced.

[AbstractionAnon]

On entering f(n) for the second problem, you need to calculate 8^n.
You'll need a loop to do that.
Then call f(n-1) and add the result.
Does that help?

[greenleaf800073]

Here you go chap:

#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

int b(int base)
{
    int a = 0;
    int n = 1;
    for(int nN = 0;nN < base;nN++)
    {
    a = n * n * n + a;
    n++;
    }
    return a;
}

int e(int base,int exponent)
{
    int a = base;
    int b = base;
    int n = 1;
    int c = 0;
    for(int nN = 0;nN < exponent;nN++)
    {
        for(int nN2 = 1;nN2 < n;nN2++)
        {
            a = a * b;
        }
        c += a;
        a = base;
        n++;
    }
    return c;
}

int main(int nNumberofArgs,char* pszArgs[])
{
    char input;
    int base;
    int exponent;
    int output;
    cout << "This is a recursive math program.\nEnter b to change base. Enter e to change exponents:";
    cin >> input;

    switch(input)
    {
        case 'b':
        case 'B':
            cout << "1^3+2^3+3^3...n^3" << endl;
            cout << "Enter base: ";
            cin >> base;
            output = b(base);
            break;
        case 'e':
        case 'E':
            cout << "b^1+b^2+b^3...b^n" << endl;
            cout << "Enter base: ";
            cin >> base;
            cout << "Enter exponent: ";
            cin >> exponent;
            output = e(base,exponent);
            break;
        default:
            cout << "Please enter 'b' or 'e'";
            break;
    }
    cout << "Output = " << output << endl;
    system("PAUSE");
    return 0;
}

I like helping people :)

[Lowest0ne]

@greenleaf800073: This needs to be recursive.

I don't understand this:

if (n == 5)
{
	return 0;
}

What kind of condition is that? Is this what your teacher gave you?

[greenleaf800073]

@lowestone: Uh You mean ND04 right? Because I fixed that in my code.

[cire]

greenleaf8000073 wrote:

@lowestone: Uh You mean ND04 right? Because I fixed that in my code.

I believe what he meant is that the OP requires a recursive solution and yours is not.

http://danzig.jct.ac.il/cpp/recursion.html