Thank you for the additional information. Since the Officer(s) arrived after the fact, they can not testify at the trial as to your driving pattern and if in fact it was careless. Only you and the other driver/witnesses, could testify to what happened. With that being said, if the other party fails to show at trial, then the case would be dismissed, since there is nobody to oppose your testimony and the Officer(s) were after the fact. Now, if they do appear, then it will be your word against them and up to the Judge to decide, in regard to your driving being "careless" as alleged. If the cars were parked illegal, this could be a mitigating factor to use in your defense and opposition to the citation. In order to prevail, the State must prove the following:
39:4-97. Careless driving
39:4-97. A person who drives a vehicle carelessly, or without due caution and circumspection, in a manner so as to endanger, or be likely to endanger, a person or property, shall be guilty of careless driving.
As such, you would need to show that these elements were not present and the result was from the other party and/or illegally parked cares.