#### Flood Fill

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```/**
* Flood fill.
*
* Flood fill, also called seed fill, is an algorithm that determines and alters the area connected to a given node in a
* multi-dimensional array with some matching attribute. It is used in the "bucket" fill tool of paint programs to fill
* connected, similarly-colored areas with a different color.
*
* (description adapted from https://en.wikipedia.org/wiki/Flood_fill)
* @see https://www.techiedelight.com/flood-fill-algorithm/
*/

const neighbors = [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]]

/**
* Implements the flood fill algorithm through a breadth-first approach using a queue.
*
* @param rgbData The image to which the algorithm is applied.
* @param location The start location on the image.
* @param targetColor The old color to be replaced.
* @param replacementColor The new color to replace the old one.
*/
export function breadthFirstSearch (rgbData, location, targetColor, replacementColor) {
if (location[0] < 0 ||
location[0] >= rgbData.length ||
location[1] < 0 ||
location[1] >= rgbData[0].length) {
throw new Error('location should point to a pixel within the rgbData')
}

const queue = []
queue.push(location)

while (queue.length > 0) {
breadthFirstFill(rgbData, location, targetColor, replacementColor, queue)
}
}

/**
* Implements the flood fill algorithm through a depth-first approach using recursion.
*
* @param rgbData The image to which the algorithm is applied.
* @param location The start location on the image.
* @param targetColor The old color to be replaced.
* @param replacementColor The new color to replace the old one.
*/
export function depthFirstSearch (rgbData, location, targetColor, replacementColor) {
if (location[0] < 0 ||
location[0] >= rgbData.length ||
location[1] < 0 ||
location[1] >= rgbData[0].length) {
throw new Error('location should point to a pixel within the rgbData')
}

depthFirstFill(rgbData, location, targetColor, replacementColor)
}

/**
* Utility-function to implement the breadth-first loop.
*
* @param rgbData The image to which the algorithm is applied.
* @param location The start location on the image.
* @param targetColor The old color to be replaced.
* @param replacementColor The new color to replace the old one.
* @param queue The locations that still need to be visited.
*/
function breadthFirstFill (rgbData, location, targetColor, replacementColor, queue) {
const currentLocation = queue[0]
queue.shift()

if (rgbData[currentLocation[0]][currentLocation[1]] === targetColor) {
rgbData[currentLocation[0]][currentLocation[1]] = replacementColor

for (let i = 0; i < neighbors.length; i++) {
const x = currentLocation[0] + neighbors[i][0]
const y = currentLocation[1] + neighbors[i][1]
if (x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length) {
queue.push([x, y])
}
}
}
}

/**
* Utility-function to implement the depth-first loop.
*
* @param rgbData The image to which the algorithm is applied.
* @param location The start location on the image.
* @param targetColor The old color to be replaced.
* @param replacementColor The new color to replace the old one.
*/
function depthFirstFill (rgbData, location, targetColor, replacementColor) {
if (rgbData[location[0]][location[1]] === targetColor) {
rgbData[location[0]][location[1]] = replacementColor

for (let i = 0; i < neighbors.length; i++) {
const x = location[0] + neighbors[i][0]
const y = location[1] + neighbors[i][1]
if (x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length) {
depthFirstFill(rgbData, [x, y], targetColor, replacementColor)
}
}
}
}
```