Flood fill, also called seed fill, is an algorithm that determines the area that are connected to a given node in a multi-dimensional array. It is used in the "bucket" fill tool of paint programs to determine which parts of a bitmap to fill with color, and in puzzle games such as Puyo Puyo, Lumines, Magical Drop, and some implementations of Tetris (but not Columns) for determining which pieces are cleared. An explicitly queue-based implementation might resemble the following: