Print all subsets of given size of a set in C++

In this problem, we are given an array and we have to print all the subset of a given size r that can be formed using the element of the array.

Let’s take an example to understand the topic better −

Input:
array = {3, 5, 6}
r = 2
Output:
3 5
3 6
5 6

In this problem, we will have to find all the combinations of the numbers of the array. And exclude those r bit combinations which are already in the set.

Example

 Live Demo

#include <iostream>
using namespace std;
void printSubset(int arr[], int n, int r, int index, int data[], int i);
int main(){
   int arr[] = {3 , 5, 6};
   int r = 2;
   cout<<"The sets are : ";
   int n = sizeof(arr) / sizeof(arr[0]);
   int data[r];
   printSubset(arr, n, r, 0, data, 0);
   return 0;
}
void printSubset(int arr[], int n, int r, int index, int data[], int i){
   if (index == r) {
      for (int j = 0; j < r; j++)
         cout<<data[j]<<" ";
      cout<<endl;
      return;
   }
   if (i >= n)
      return;
   data[index] = arr[i];
   printSubset(arr, n, r, index + 1, data, i + 1);
   printSubset(arr, n, r, index, data, i + 1);
}

Output

The sets are −

3 5
3 6
5 6