The Algorithm
The flood fill algorithm takes three parameters: a start node, a target color, and a replacement color. The algorithm looks for all nodes in the array which are connected to the start node by a path of the target color, and changes them to the replacement color. There are many ways in which the flood-fill algorithm can be structured, but they all make use of a queue or stack data structure, explicitly or implicitly.
Depending on whether we consider nodes touching at the corners connected or not, we have two variations, Eight-way and Four-way, respectively.
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