Hill finished with 18 points while Brandon Ashley and Kaleb Tarczewski added 10 apiece for the Wildcats (19-2, 7-2 Pac-12), who outscored their opponents 40-26 in the first half to grab control.
The victory was the third straight for Arizona.
Brock Motum provided 15 points and six rebounds and DaVonte Lacy also scored 15 points for the Cougars (11-11, 2-7).
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