import java.util.*;

public class PermutationSeating4 {

    static int count;

    public static void main (String[] argv)
    {
        // Test case 1
	int numSeats = 3;
	int numPeople = 2;
	int[] seats = new int [numSeats];
	count = 0;
	printPermutations (numSeats, numPeople, seats, 1);
	System.out.println ("  => " + count + " permutations");

        // Test case 2
	numSeats = 5;
	numPeople = 2;
	seats = new int [numSeats];
	count = 0;
	printPermutations (numSeats, numPeople, seats, 1);
	System.out.println ("  => " + count + " permutations");
    }

    static void printPermutations (int numSpaces, int numRemaining, int[] seats, int person)
    {
	if (numRemaining == 0) {
	    // Print.
	    System.out.println ( Arrays.toString(seats) );
	    count ++;
	    return;
	}

	// Look for an empty spot for this person.
	for (int i=0; i<seats.length; i++) {

            // Check for "banned" configuration:
	    if (person == 1) {
		if ( (i == 0) || (i == seats.length-1) ) {
                    // Person 1 can't sit at the ends.
		    // Skip to next loop iteration.
		    continue;
		}
	    }

            // We reach here if it's ok to explore further.
	    if (seats[i] == 0) {
		// Empty spot.
		seats[i] = person;
		printPermutations (numSpaces-1, numRemaining-1, seats, person+1);
		seats[i] = 0;
	    }
	}
    }

}