c++ - generate all subsets of size k from a set

Question

I want to generate all the subsets of size k from a set.

eg:-say I have a set of 6 elements, I have to list all the subsets in which the cardinality of elements is 3.

I tried looking for solution,but those are code snippets. Its been long since I have done coding,so I find it hard to understand the code and construct a executable program around it.

A complete executable program in C or C++ will be quite helpful. Hoping of an optimal solution using recursion.

Answer 1

Find a working code below

#include<iostream>
#include<string>
#include<list>

using namespace std;

void print( list<int> l){
    for(list<int>::iterator it=l.begin(); it!=l.end() ; ++it)
            cout << " " << *it;
    cout<<endl;
}

void subset(int arr[], int size, int left, int index, list<int> &l){
    if(left==0){
        print(l);
        return;
    }
    for(int i=index; i<size;i++){
        l.push_back(arr[i]);
        subset(arr,size,left-1,i+1,l);
        l.pop_back();
    }

}     

int main(){
    int array[5]={1,2,3,4,5};
    list<int> lt;   
    subset(array,5,3,0,lt);


    return 0;
}