/**
     * Merges the keywords for a single document into the master keywordsIndex
     * hash table. For each keyword, its Occurrence in the current document
     * must be inserted in the correct place (according to descending order of
     * frequency) in the same keyword's Occurrence list in the master hash table.
     * This is done by calling the insertLastOccurrence method.
     *
     * @param kws Keywords hash table for a document
     */
    public void mergeKeyWords(HashMap<String,Occurrence> kws) {
        // COMPLETE THIS METHOD


        // keywordsIndex.get(key).add(Occurrence)
        // ketwordsIndex.get(key).insertLastOccurence()
    }


/**
     * Inserts the last occurrence in the parameter list in the correct position in the
     * same list, based on ordering occurrences on descending frequencies. The elements
     * 0..n-2 in the list are already in the correct order. Insertion is done by
     * first finding the correct spot using binary search, then inserting at that spot.
     *
     * @param occs List of Occurrences
     * @return Sequence of mid point indexes in the input list checked by the binary search process,
     *         null if the size of the input list is 1. This returned array list is only used to test
     *         your code - it is not used elsewhere in the program.
     */
    public ArrayList<Integer> insertLastOccurrence(ArrayList<Occurrence> occs) {
        if (occs.isEmpty() || occs.size() == 1)
            return null;

        Occurrence last = occs.get(occs.size()-1);

        ArrayList<Integer> checked = new ArrayList();

        int hi = occs.size() - 2; //last position is element to be sorted
        int lo = 0;
        int mid = 0;
        while (lo <= hi) {
            mid = (lo + hi)/2;
            checked.add(mid);
            if(last.frequency == occs.get(mid).frequency)
                break;
            else if (last.frequency > occs.get(mid).frequency)
                hi = mid - 1;
            else
                lo = mid + 1;
        }
        occs.add(mid, last);
        occs.remove(occs.size()-1);

        return checked;
    }