Quarterback Brock Purdy had three first-half touchdown passes to lead No. 17 Iowa State past visiting Kansas State 45-0 in Ames, Iowa.Purdy finished with 236 yards on 16-of-20 passing. Breece Hall, the nation’s leading rusher coming into the game, added 135 yards and two rushing touchdowns, including 123 rushing yards and both touchdowns in the first half.Iowa State (6-2, 6-1 Big 12), alone in first place in the Big 12 Conference, improved its chances to play in the conference championship game. The Cyclones are seeking their first conference championship since winning the Missouri Valley Conference title in 1912. They play at No. 22 Texas next Saturday before closing the season with a home game against West Virginia.Iowa State had a 539-149 advantage in total offense. The Cyclones had 10 tackles-for-loss and forced three Kansas State turnovers. It was the first time the Wildcats have been shut out since 2015.Kansas State (4-4, 4-3 Big 12), playing without starting linebackers Elijah Sullivan and Justin Hughes because of COVID, lost its third straight game. Quarterback Will Howard was 3 of 9 for 32 yards and a pick before getting knocked out of the game in the first half.Iowa State wasted little time in jumping out to the lead. Purdy found Joe Scates for a 33-yard touchdown pass and a 7-0 lead just three minutes into the game. The score capped a six-play, 75-yard drive.