public void initializeUserFriends() {
		userFriends = new TreeMap<Integer, HashSet<Integer>>();
		for (int i = 0; i < friends.length; i++) {
			if (friends[i][0] == friends[i][1]) { // User with no friends
				HashSet<Integer> hs = new HashSet<Integer>();
				userFriends.put(friends[i][0], hs);
			} else { // User with friends
				if (userFriends.containsKey(friends[i][0])) {
					userFriends.get(friends[i][0]).add(friends[i][1]);
				} else {
					HashSet<Integer> hs = new HashSet<Integer>();
					hs.add(friends[i][1]);
					userFriends.put(friends[i][0], hs);
				}
				if (userFriends.containsKey(friends[i][1])) {
					userFriends.get(friends[i][1]).add(friends[i][0]);
				} else {
					HashSet<Integer> hs = new HashSet<Integer>();
					hs.add(friends[i][0]);
					userFriends.put(friends[i][1], hs);
				}
			}
		}
	}