Convert to Non-recursive

#include <iostream>
using namespace std;
 
void comb(int n, int r, int *arr, int sz) {
    for (int i = n; i >= r; i --) {
        // choose the first element
        arr[r - 1] = i;
        if (r > 1) { // if still needs to choose
            // recursive into smaller problem
            comb(i - 1, r - 1, arr, sz);
        } else {        	
            // print out one solution
            for (int i = 0; i < sz; i ++) {
                cout << arr[i] << " ";
            }
            cout << endl;
        }
    }
}
 
int main() {
    const int N = 4;
    int *arr = new int[3];
    for(int i=1;i<=N;i++)
    	comb(N, i, arr, i);
    return 0;
}

*Result
1
2
3
4
1 3
1 2
1 4 
2 3 
2 4
3 4
1 2 3
1 2 4
1 3 4
2 3 4
1 2 3 4