# C++ Program to Generate All Possible Combinations Out of a,b,c,d,e

This is a C++ program to generate all possible combinations out of a, b, c, d, e.

## Algorithms

Begin
Take the number of elements and the elements as input.
function Combi(char a[], int reqLen, int s, int currLen, bool check[], int l)
to print the all possible combination of given array set:
//
Here,
char a[] = character array
reqLen = required length
s = start variable
currLen = current length
check[] = a boolean variable
l = length of array
//
Body of the Function:
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 option:
either proceed with a start as ‘true’ and recursively call Combi() with incremented value of ‘currLen’ and ‘s’.
Or proceed with a start as ‘false’ and recursively call Combi() with only incremented value of ‘s’.
End

## Example

#include<iostream>
using namespace std;
void Combi(char a[], int reqLen, int s, int currLen, bool check[], int l)
{
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<<"\n";
return;
}
if (s == l) {
return;
}
check[s] = true;
Combi(a, reqLen, s + 1, currLen + 1, check, l);
check[s] = false;
Combi(a, reqLen, s + 1, currLen, check, l);
}
int main() {
int i,n;
bool check[n];
cout<<"Enter the number of element array have: ";
cin>>n;
char a[n];
cout<<"\n";
for(i = 0; i < n; i++) {
cout<<"Enter "<<i+1<<" element: ";
cin>>a[i];
check[i] = false;
}
for(i = 1; i <= n; i++) {
cout<<"\nThe all possible combination of length "<<i<<" for the given array set:\n";
Combi(a, i, 0, 0, check, n);
}
return 0;
}

## Output

Enter the number of element array have: 5
Enter 1 element: a
Enter 2 element: b
Enter 3 element: c
Enter 4 element: d
Enter 5 element: e
The all possible combination of length 1 for the given array set:
a
b
c
d
e
The all possible combination of length 2 for the given array set:
a b
a c
a d
a e
b c
b d
b e
c d
c e
d e
The all possible combination of length 3 for the given array set:
a b c
a b d
a b e
a c d
a c e
a d e
b c d
b c e
b d e
c d e
The all possible combination of length 4 for the given array set:
a b c d
a b c e
a b d e
a c d e
b c d e
The all possible combination of length 5 for the given array set:
a b c d e