new_lesson7_2

#include <iostream>

using namespace std;

int factorial(int n) {
    if (n < 1)
        return 0;
    if (n == 1)
        return 1;
    int res = 1;
    for (; n > 1; n--)
        res *= n;
    return res;
}

int fun1(int n) {
    if (n == 1)
        return 1;
    return n * fun1(n-1);
}

int sum(int n) {
    if (n == 1) return 1;
    return n + sum(n - 1);
}

int sumArr(int arr[], int sz) {
    if (sz == 1) return arr[0];
    return arr[sz - 1] + sumArr(arr, sz-1);
}

void showArr(int arr[], int sz) {
    if (sz == 1)
        cout << arr[0];
    else {
        cout << arr[sz - 1] << " ";
        showArr(arr, sz - 1);
    }
}

double power(double x, int n) {
    if (n == 0) return 1;
    if (n == 1) return x;
    return x * power(x, n - 1);
}

void main() {
    cout << "Iteration VS Recursion" << endl;
    cout << "5! = " << factorial(5) << endl;
    cout << "5! = " << fun1(5) << endl;
    cout << "3^4 = " << power(3, 4) << endl;
    cout << sum(5) << endl;

    int arr[4]{ 3, 5, 2, 1 };
    cout << sumArr(arr, 4) << endl;
    showArr(arr, 4);
    cout << endl;

}