Riller, who entered averaging 16 points and four assists, has six career 30-or-more-point games.
Jarrell Brantley added 15 points for the Cougars (4-2).
Charleston and Memphis will meet in Sunday’s fifth-place game.
UAB (3-2) got 11 points apiece Lewis Sullivan and Jeremiah Bell.
The Blazers will take on Canisius Sunday for seventh place.
Riller had 16 points as Charleston went up 30-18 at the half.
Mfiondu Kabengele hit a 3-pointer with a half-second left in overtime, and No. 14 Florida State advanced to the championship game of the AdvoCare Invitational with a 79-76 win over No. 19 LSU on Friday.
The Seminoles (5-0) will play defending national champion Villanova on Sunday.
Tremont Waters made three free throws to pull LSU even at 76 with 11.5 seconds to go in overtime before Kabengele’s shot from the corner bounced off the rim and into the basket.
After trailing by nine, Florida State forced overtime when Trent Forrest tied it at 68-68 on a layup with 2.8 seconds left.
Naz Reid’s 3-pointer at the buzzer hit off the rim for LSU.
Reid hit a 3 and Emmitt Williams had a fast-break dunk as LSU went up 59-52 with 7½ minutes left.
M.J. Walker had 13 first-half points as Florida State took a 30-29 lead at the break.
LSU (5-1) will go against Oklahoma State in Sunday’s third-place game.
Kyvon Davenport scored 16 points and grabbed 10 rebounds for his 10th career double-double, and Memphis beat Canisius 71-63 in a consolation-round game at the AdvoCare Invitational on Friday.
Mike Parks and Antwann Jones both had 14 points for Memphis (3-2), which will play the winner of UAB-Charleston in the fifth-place game Sunday. The Tigers lost 84-64 to Oklahoma State Thursday.
Canisius (1-4) got 18 points from Takal Molson and Isaiah Reese had 14.
The Golden Griffins will look to avoid losing all three games at the invitational when they face the loser of UAB-Charleston Sunday for seventh place.
Canisius opened the tournament Thursday with an 83-56 loss to defending national champion Villanova.
Jones had 10 points to help Memphis go up 40-31 at halftime.
Eric Paschall had 22 points and Phil Booth added 20 as Villanova advanced to the title game of the AdvoCare Invitational by beating Oklahoma State 77-58 on Friday.
The Wildcats, who made a tournament record 16 3-pointers, will play on Sunday against the winner of No. 14 Florida State’s game against No. 19 LSU.
Villanova (4-2) stopped a two-game skid by beating Canisius 82-56 in Thursday’s first round.
Mike Cunningham scored 15 points for Oklahoma State (3-2).
Paschall had 20 points, including six 3-pointers, as Villanova took a 42-26 halftime advantage. The Wildcats, who led by as many as 18 points, went 10 for 24 from 3-point range during the half.
Oklahoma State got within 13 before Dhamir Cosby-Roundtree’s dunk put Villanova up 71-56 with two minutes remaining.
Booth’s 3-pointer gave Villanova a 54-29 lead four minutes into the second half.
Oklahoma State closed to 60-47 on Cunningham’s 3 with 8½ minutes to go.
The Cowboys will face the Florida State-LSU loser Sunday for third place.
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