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

// Selects a random value from the array giving the last value a 50%
// chance to be selected, the previous to last 25%, and so on. Used as
// an example of tail recursion.
int randomSelect (int A[], int size) 
{
    if (size == 0)
        return -1;
    else if (size == 1)
        return A[0];
    else if (rand() % 2 == 0)
        return A[size-1];
    else
        return randomSelect(A, size-1);
}

// Outputs the numbers from n down to 0 recursively.
void printN(int n)
{
    if (n < 0)
        cout << endl;
    else 
    {
        cout << n << " ";
        printN(n - 1);
    }
}

// Counts the occurrences of the value in the array using recursion.
int countVal (int A[], int size, int val)
{
    if (size == 0)
        return 0;
    else if (A[size - 1] == val)
        return 1 + countVal(A, size-1, val);
    else
        return countVal(A, size - 1, val);
}

// Testing for the random select function.
int main()
{
    int arr[] = {12, 3, 6, 7, 2, 9};
    int brr[] = {1, 3, 2, 7, 1, 7, 2, 7};
    srand(time(NULL));
    cout << "Selection: " << randomSelect(arr, 6) << endl;
    printN(8);
    cout << "Count of 7 in brr: " << countVal(brr, 8, 7) << endl;
    return 0;
}