I need to do a hwk using recursion concept. You should use only C. Description:

Question

I need to do a hwk using recursion concept.

You should use only C.

Description:

You will find that recursion is used a lot for mathematical problems. While it’s not the only use for it, it’s the easiest way to learn recursion. Now, most of these problems are google-able. I assure you that the lab this week you cannot find on google, so if you do cheat and look up the prelab, you aren’t helping yourself learn this.

Part 1:

A factorial, denoted X!, is all numbers from 1-X inclusive multiplied together. For example:

5! = 5*4*3*2*1 = 120

Write a recursive function that calculates the factorial of a number. You should use the following prototype:

                           int factorial(int num);

Where it takes a number you want the factorial for, and returns the final answer.

Part 2:

Calculating the cost of a task that takes many identical steps can be expressed as so:

f(x) = f(x-1) + g(x),

Where f(x) is the cost of doing a task with x steps, and g(x) is the cost of doing that particular step.

Say you have such a task with the following cost function:

f(x) = f(x-1) + 4x, where f(0) = 2 and f(1) = 5

Write a recursive function that calculates the total cost of such a task. Use the following prototype:

                           int costFunction(int num);

Where it takes a number of steps in the task and returns the final cost.

Explanation / Answer

#include int factorial(int); int main() { int num; int result; printf("Enter a number to find it's Factorial: "); scanf("%d", &num); if (num < 0) { printf("Factorial of negative number not possible "); } else { result = factorial(num); printf("The Factorial of %d is %d. ", num, result); } return 0; } int factorial(int num) { if (num == 0 || num == 1) { return 1; } else { return(num * factorial(num - 1)); } }

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