North Carolina had only a one-point lead 4 minutes deep in the second half, but the Tar Heels then ran off seven points in a row in a span of 1:44 to take control.
McAdoo scored 18 points and had nine rebounds, P.J. Hairston had 14 points and Marcus Paige contributed 14. The Tar Heels (3-0) shot only 40 percent from the field.
James Ennis paced the 49ers (1-2) with 18 points. Long Beach State could make just 5-of-25 shots from 3-point range.