#include <stdio.h>
void combinationUtil(int arr[], int data[], int start, int end,
                     int index, int r)
{
    // Current combination is ready to be printed, print it
    if (index == r)
    {
        int w = 0;
        int j = 0;
        while ( j<r ) {
        printf("%d", data[j]);

            j++;
        }
        printf("\n");

        return;
    }

    // replace index with all possible elements. The condition
    // "end-i+1 >= r-index" makes sure that including one element
    // at index will make a combination with remaining elements
    // at remaining positions
    for (int i=start; i<=end && end-i+1 >= r-index; i++)
    {
        data[index] = arr[i];
        combinationUtil(arr, data, i+1, end, index+1, r);
    }
}


void printCombination(int arr[], int n, int r)
{
    // A temporary array to store all combination one by one
    int data[r];

    // Print all combination using temprary array 'data[]'
    combinationUtil(arr, data, 0, n-1, 0, r); }

/* arr[]  ---> Input Array
   data[] ---> Temporary array to store current combination
   start & end ---> Staring and Ending indexes in arr[]
   index  ---> Current index in data[]
   r ---> Size of a combination to be printed */


// Driver program to test above functions
int main()
{
    int arr[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    int r = 2;
    int n = (&arr)[1] - arr;
    printCombination(arr, n, r);
}