#include <string>
#include <iostream>
void print_str(const char*,std::string,const int, const int);
int main()
{
int lenght = 2;
char str[] = {'A', 'B', 'C', 'D'};
int n = sizeof str;
print_str(str, "", n, lenght); //Note: this function works on all cases and not just the case above
return 0;
}
// The main recursive method to print all possible strings of length "length"
void print_str(const char str[],std::string prefix,const int n, const int lenght)
{
if (lenght == 1)
{
for (int j = 0; j < n; j++)
std::cout << prefix + str[j] << std::endl;
}//Base case: lenght = 1, print the string "lenght" times + the remaining letter
else
{
// One by one add all characters from "str" and recursively call for "lenght" equals to "lenght"-1
for (int i = 0; i < n; i++)
// Next character of input added
print_str(str, prefix + str[i], n, lenght - 1);
// "lenght" is decreased, because we have added a new character
}
}