Program Mencari Kombinasi Dengan Bahasa C++

#include <iostream>
void combinate(char a[], int perm[],int index, int n, int k)
{
   static int count = 0;
   if( count == k )
   {
      for(int i=0; i<n; i++)
        if( perm[i]==1)
          printf("%c",a[i]);
      printf("\n");
    } else if( (n-index)>= (k-count) ){
         perm[index]=1;
         count++;
         combinate(a,perm,index+1,n,k);
         perm[index]=0;
         count--;
         combinate(a,perm,index+1,n,k);
   }
}
int main()
{
   char a[] ={'a','b','c'};
   int perm[4] = {0};
   combinate(a,perm,0,4,3);
   return 0;
}