Sichuan Mahjong Ext

It is a game which erases all the same tiles by two pairs.
It is familiar as a game with two corners.
The erasable tile is when the tile and tile are in a position where they can be connected by three straight lines below.
The grade is decided by the time when all the tiles are erased.
As a function,
(1) Always put all tiles
(2) Display tiles that can be deleted (Displays the number of tiles that can be erased)
(3) You can return to the state before erasing
(4) Display the top 100 of the grade time