РЕКУРСИЯ

#include <iostream>
using namespace std;

void pow2(int n) {
    if (n >= 2) {
        if (n % 2 == 0) {
            n /= 2;
            cout << " " << n;
            pow2(n);
        }
        else cout << "\n no <3" << endl;

        if (n == 2) {
            cout << "\n yasss" << endl;
        }
    }
}

int t = 0;
void digit_sum(int m) {

    t += m % 10;
    m /= 10;

    if (m > 9) {
        digit_sum(m);
    }
    else {
        cout << t + m;
    }

}

void reverse(int k) {

    cout << " " << k % 10;
    k /= 10;

    if (k > 9) {
        reverse(k);
    }
    else {
        cout << " " << k;
    }
}

int k = 0;
void row(int j) {

    k++;

    if (j != 1) {
        for (int i = 0; i < k; i++) {
            cout << " " << k;
            if (i == j) exit(0);
            else if (i + 1 == k and k != j) {
                row(j);
                exit(0);
            }

        }
    }
}

int main() {

    int x;
    cout << "choose the program (1-4): " << endl;
    cin >> x;

    switch (x) {
        case 1:
            cout << "enter the number(pow2): " << endl;
            int n;
            cin >> n;
            pow2(n);
            break;

        case 2:
            cout << "\n enter the number(digit_sum): " << endl;
            int m;
            cin >> m;
            digit_sum(m);
            break;

        case 3:
            cout << "\n enter the number(reverse): " << endl;
            int k;
            cin >> k;
            reverse(k);
            break;

        case 4:
            cout << "\n enter the number(row): " << endl;
            int j;
            cin >> j;
            row(j);
            break;
    }

}