(C++) Use recursion to find how many ancestors you have up to a certain number o

Question

(C++)

Use recursion to find how many ancestors you have up to a certain number of generations back. For example, 1 generation back is how many parents people have on average. 2 generations back correspond to the average number of grand parents. For our purpose, a child of a “single parents” have only one parent. A child with a parent that divorced but then remarried will have 3 parents (2 biological and one step). All other children will have two parents. Assume about 1/3 of children have a single parent, and 2/9 have 3 parents. Ask the user how many generations back you want to look. Then simulate the number of parents based on the probabilities above a million times to find the average. The computer will take a bit of time to think for these problems, so it is advised that you only test on small numbers on slower machines. Hint: you might want to use a double to help find the average.

Example 1 (user input is underlined):

How many generations back? 1

There are approximately 1.88881 people 1 generations back on average

Explanation / Answer

#include <iostream>
#include <cstring>

using namespace std;

double find(int n)
{
if(n==0)
return 1;

return (1.0/3)*find(n-1) + (2.0/9)*find(n-1)*3 + (4.0/9)*find(n-1)*2;
}
int main()
{
int n;
cout<<"How many generations back? ";
cin>>n;
cout<<"There are approximately "<<find(n)<<" people "<<n<<" generations back on average ";
return 0;
}

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