Champions League 2012/2013 1/16 draw simulation. Total 5463 possibilities.

ChampionsLeague.java

import com.google.common.collect.Collections2;
import java.util.*;
public class ChampionsLeague {
  public static class Team{
		String name, country;
		int place;
		char group;
		public Team(){}
		public Team(String name, String country, int place, char group){
			this.name=name;
			this.country=country;
			this.place=place;//first or second
			this.group=group;
		}
		public String toString(){
			return name;
		}
	}

	public static boolean isValid(Team team1, Team team2){
		boolean valid = true;
		if (team1.country.equals(team2.country)) valid = false;
		if (team1.place==team2.place) valid = false;
		if (team1.group==team2.group) valid = false;
		return valid;			
	}

	public static void main(String args[]){
		Team[] round16 = new Team[16];
		round16[0] = new Team("MU", "England", 1, 'A');
		round16[1] = new Team("Galatasaray", "Turkey", 2, 'A');
		round16[2] = new Team("PSG", "France", 1, 'B');
		round16[3] = new Team("Porto", "Portugal", 2, 'B');
		round16[4] = new Team("Schalke", "German", 1, 'C');
		round16[5] = new Team("Arsenal", "England", 2, 'C');
		round16[6] = new Team("Malaga", "Spain", 1, 'D');
		round16[7] = new Team("AC", "Italy", 2, 'D');
		round16[8] = new Team("Dortmund", "German", 1, 'E');
		round16[9] = new Team("Real", "Spain", 2, 'E');
		round16[10] = new Team("Juve", "Italy", 1, 'F');
		round16[11] = new Team("Shakta", "Ukraine", 2, 'F');
		round16[12] = new Team("Bayern", "German", 1, 'G');
		round16[13] = new Team("Valencia", "Spain", 2, 'G');
		round16[14] = new Team("Barca", "Spain", 1, 'H');
		round16[15] = new Team("Celtic", "scotland", 2, 'H');

		Team[] first = new Team[8];
		Team[] second = new Team[8];
		for (int i=0; i<16; i++){
			if (i%2==0) first[i/2]=round16[i];
			else second[i/2]=round16[i];
		}
		ArrayList<Team> teamSecond = new ArrayList<Team>(Arrays.asList(second));
		Collection<List<Team>> permuted = Collections2.permutations(teamSecond);

		@SuppressWarnings("unchecked")
		List<Team>[] permutedList = permuted.toArray(new List[40320]);
		Team[][] permutedArray = new Team[40320][8];
		for (int i = 0; i < 40320; i++) {
			permutedArray[i] = permutedList[i].toArray(new Team[8]);
		}
		
		int count = 0;
		for (int i=0; i<permutedArray.length; i++){
			boolean valid = true;
			for (int j=0; j<8; j++){
				if(!isValid(first[j], permutedArray[i][j])){
					valid = false;
					break;
				}
			}
			if (valid) count++;
		}		
		System.out.println("Total " + count+ " possibilities");
	}
}