This Demonstration compares the iterative and recursive Flood Fill algorithm. The recursive algorithm searches for a blank cell in four directions (north, west, south, east), then fills that cell, and continues to look for another blank cell in the same four directions. It will always search for north, west, south, east in that order. For example, if both west and south are available, it will fill the west cell. Finally, if all compass directions are filled, then it will go back to the previous cell it was at and start filling if there are any cell in the compass direction that are not filled. The iterative algorithm looks for a blank cell in two directions (south and north), fills the blank cell, and adds the blank cells that are to the west or east of it to a queue. Then while the queue is not empty, the step is repeated. The white cells represent blank cells, blue cells represent filled cells, and black cells represent obstacles.