// In a permutation, the subset elements are listed in a specific order.
class TwoLettersPermutationFromABCD_Java {
private static void create_2_letters_permutation( char[] letters) {
int size = letters.length;
for (int i = 0; i < size; i++) {
for (int j = 0; j < size; j++) {
if (i != j) {
System.out.format("%c%c\n", letters[i], letters[j]);
}
}
}
}
public static void main(String[] args) {
char[] letters = {'A', 'B', 'C', 'D'};
create_2_letters_permutation(letters);
}
}
/*
run:
AB
AC
AD
BA
BC
BD
CA
CB
CD
DA
DB
DC
*/