OLL 20 algorithm: X, Checkers
OLL (orient the last layer). Group: Dot (no edges oriented).
OLL 20, X: yellow stickers on the top face: back-left corner, back-right corner, centre, front-left corner, front-right corner. Yellow stickers on the sides: back face, centre, right face, middle, front face, centre, left face, middle.
The diagram shows the cube from above with the front at the bottom and yellow on top.
Algorithm
r U R' U' M2 U R U' R' U' M'
11 moves.
Other algorithms
r' R U R U R' U' r R' M' U R U' r'M' U2 M U2 M' U M U2 M' U2 MS' R U R' S U' M' U R U' r'
Source: www.speedcubedb.com