Johnson also had a game-high six assists for the Wildcats (5-0), who will take on Drexel on Nov. 27 in the semifinals of the tournament.
Freshman Rondae Hollis-Jefferson chipped in 13 points for Arizona and Aaron Gordon scored 12.
Xavier Munford scored 22 points, but was the only Rhode Island (3-2) player in double figures. The Rams were stymied by Arizona's defense early on and only mustered six points in the first 10:23 of the game.
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