#### Flood Fill

A
P
```/**
* 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.
*
* @see https://www.techiedelight.com/flood-fill-algorithm/
*/

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

function isInside(rgbData, location) {
const x = location[0]
const y = location[1]
return x >= 0 && x < rgbData.length && y >= 0 && y < rgbData[0].length
}

function checkLocation(rgbData, location) {
if (!isInside(rgbData, location)) {
throw new Error('location should point to a pixel within the rgbData')
}
}

function* neighbors(rgbData, location) {
for (const offset of neighborOffsets) {
const neighborLocation = [location[0] + offset[0], location[1] + offset[1]]
if (isInside(rgbData, neighborLocation)) {
yield neighborLocation
}
}
}

/**
* 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.
*/
rgbData,
location,
targetColor,
replacementColor
) {
checkLocation(rgbData, location)

const queue = []
queue.push(location)

while (queue.length > 0) {
}
}

/**
* 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
) {
checkLocation(rgbData, location)

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.
*/
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 (const neighborLocation of neighbors(rgbData, currentLocation)) {
queue.push(neighborLocation)
}
}
}

/**
* 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 (const neighborLocation of neighbors(rgbData, location)) {
depthFirstFill(rgbData, neighborLocation, targetColor, replacementColor)
}
}
}
```