2013b_92que1

public static int longestFlat(int[] arr)
    {
        return longestFlat(arr, 0);
    }

    private static int longestFlat(int[] a, int i)
    {
        if(i == a.length)
            return 0;
        int thisFlat = flatLength(a, i, a[i], false, 0);
        int nextFlat = longestFlat(a, i + 1);
        return Math.max(thisFlat, nextFlat);
    }

    private static int flatLength(int[] a, int i, int start, boolean hasNextValue, int nextValue)
    {
        if(i == a.length)
            return 0;
        if(a[i] != start)
            if(hasNextValue){
                if(a[i] != nextValue)
                    return 0;
            }
            else{
                if(Math.abs(start - a[i]) != 1)
                    return 0;
                return 1 + flatLength(a, i + 1, start, true, a[i]);
            }
        return 1 + flatLength(a, i + 1, start, hasNextValue, nextValue);
    }