Plus One

def plusOne(self, digits):
    """
    :type digits: List[int]
    :rtype: List[int]
    """
    for i in range(len(digits) - 1, -1, -1):
        if digits[i] < 9:
            digits[i] += 1
            return digits
        digits[i] = 0
    return [1] + digits