public static List<Integer> rotLeft(List<Integer> a, int d) {
    int length = a.size();
    if (length < 2) {
        return a;
    }        
    Integer[] rotatedArray= new Integer[length];
    for(int i=0;i<length;i++){
        int target_index = (length - d + i);
        if (target_index > length - 1) {
            target_index = i - d;
        }
        rotatedArray[target_index] = a.get(i);
    }
    return Arrays.asList(rotatedArray);
}