print_all_subset

#include <bits/stdc++.h>
using namespace std;
void subset(int a[], int len, int c[], int len2, int index)
{
    if (index >= len)
    {
        for (int i = 0; i < len2; ++i)
        {
            printf("%d ", c[i]);
        }
        printf("\n");

        return;
    }
    subset(a, len, c, len2, index+1);

    c[len2] = a[index];

    subset(a, len, c, len2+1, index+1);
}
int main()
{
    int a[10000];
    for(int i=0;i<3;i++)
    {
       a[i]=i+1;
    }
    int c[1000] = {0};

    subset(a, 3, c, 0, 0);
}