Use NOT_A_PROBABILITY for adding OOV words.

    // non-0. Thus, it's not meaningful to compare 10, 100, and so on.

    // TODO: Revise the logic in ForgettingCurveUtils in native code.

    private static final int UNIGRAM_PROBABILITY_FOR_VALID_WORD = 100;

    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = 10;

    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 0;

    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = 0;

    private static final int UNIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;

    private static final int BIGRAM_PROBABILITY_FOR_VALID_WORD = 10;

    private static final int BIGRAM_PROBABILITY_FOR_OOV_WORD = Dictionary.NOT_A_PROBABILITY;

    public final String mTargetWord;

    public final int[] mWord0;