public HashMap<Integer, Set> generateUserCluster(List<User> userList) {
        HashMap<Integer, Set> userCluster;
        userCluster = new HashMap<>();
        Set<Integer> firstClusterList = new TreeSet<>();
        Set<Integer> secondClusterList = new TreeSet<>();
        Set<Integer> thirdClusterList = new TreeSet<>();
        Set<Integer> fourthClusterList = new TreeSet<>();
        Set<Integer> fifthClusterList = new TreeSet<>();
        Set<Integer> sixthClusterList = new TreeSet<>();
        for (User user : userList) {
            // int[] firstActivityCluster = user.getFirstActivityVector();
            int[] tempClassifiedTimeVector = user.getClassifiedTimeVector();
            int max = 0;
            int maxIndex = 0;
            for (int i = 0; i < tempClassifiedTimeVector.length; i++) {
                if (tempClassifiedTimeVector[i] > max) {
                    max = tempClassifiedTimeVector[i];
                    maxIndex = i;
                }
            }
            if (maxIndex == 0) {
                Integer tempuserID = user.getId();
                firstClusterList.add(tempuserID);
                userCluster.put(1, firstClusterList);
            } else if (maxIndex == 1) {
                int tempuserID = user.getId();
                secondClusterList.add(tempuserID);
                userCluster.put(2, secondClusterList);
            } else if (maxIndex == 2) {
                int tempuserID = user.getId();
                thirdClusterList.add(tempuserID);
                userCluster.put(3, thirdClusterList);
            } else if (maxIndex == 3) {
                int tempuserID = user.getId();
                fourthClusterList.add(tempuserID);
                userCluster.put(4, fourthClusterList);
            } else if (maxIndex == 4) {
                int tempuserID = user.getId();
                fifthClusterList.add(tempuserID);
                userCluster.put(5, fifthClusterList);
            } else if (maxIndex == 5) {
                int tempuserID = user.getId();
                sixthClusterList.add(tempuserID);
                userCluster.put(6, sixthClusterList);
            }
            //firstActivityCluster[maxIndex] = 1;
        }
        return userCluster;
    }