# C++ Program to Generate All Possible Subsets with Exactly k Elements in Each Subset

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This is a C++ program to generate all possible subsets with exactly k elements in each subset.

## Algorithms

Begin
function PossibleSubSet(char a[], int reqLen, int s, int currLen, bool check[], int l):
If currLen > reqLen
Return
Else if currLen = reqLen
Then print the new generated sequence.
If s = l
Then return no further element is left.
For every index there are two options:
either proceed with a start as ‘true’ and recursively call PossibleSubSet()
with incremented value of ‘currLen’ and ‘s’.
Or proceed with a start as ‘false’ and recursively call PossibleSubSet()
with only incremented value of ‘s’.
End

## Example

#include<iostream>
using namespace std;
void PossibleSubSet(char a[], int reqLen, int s, int currLen, bool check[], int l)
//print the all possible combination of given array set
{
if(currLen > reqLen)
return;
else if (currLen == reqLen) {
cout<<"\t";
for (int i = 0; i < l; i++) {
if (check[i] == true) {
cout<<a[i]<<" ";
}
}
cout<<"";
return;
}
if (s == l) {
return;
}
check[s] = true;
PossibleSubSet(a, reqLen, s + 1, currLen + 1, check, l);
//recursively call PossibleSubSet() with incremented value of ‘currLen’ and ‘s’.
check[s] = false;
PossibleSubSet(a, reqLen, s + 1, currLen, check, l);
//recursively call PossibleSubSet() with only incremented value of ‘s’.
}
int main() {
int i,n,m;
bool check[n];
cout<<"Enter the number of elements: ";
cin>>n;
char a[n];
cout<<"";
for(i = 0; i < n; i++) {
cout<<"Enter "<<i+1<<" element: ";
cin>>a[i];
check[i] = false;
}
cout<<"Enter the length of the subsets required: ";
cin>>m;
cout<<"The possible combination of length "<<m<<" for the given array set:";
PossibleSubSet(a, m, 0, 0, check, n);
return 0;
}

## Output

Enter the number of elements: 7
Enter 1 element: 7
Enter 2 element: 6
Enter 3 element: 5
Enter 4 element: 4
Enter 5 element: 3
Enter 6 element: 2
Enter 7 element: 1
Enter the length of the subsets required: 6
The possible combination of length 6 for the given array set:
7 6 5 4 3 2
7 6 5 4 3 1
7 6 5 4 2 1
7 6 5 3 2 1
7 6 4 3 2 1
7 5 4 3 2 1
6 5 4 3 2 1
Updated on 30-Jul-2019 22:30:26

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