Ex 1.

a. He attended one of schools in London.

b. He attended one of the schools in London.

Ex 2.

a. He had a dinner at one of restaurants in New York.

b.. He had a dinner at one of the restaurants in New York.

Q. Are all of the above grammatically acceptable, meaning you do not necessarily need the article "the" in front of schools/restaurants in the above cases?

Thanks in advance.