day_24b.py

#!/usr/bin/python3


def getNeighbourCount(coords, isWhiteUp):
    neighbour_increments = [(1, 1), (1, -1), (-1, 1), (-1, -1), (2, 0), (-2, 0)]
    count = 0
    for neighbour_increment in neighbour_increments:
        if (
            coords[0] + neighbour_increment[0],
            coords[1] + neighbour_increment[1],
        ) in isWhiteUp and not isWhiteUp[
            coords[0] + neighbour_increment[0], coords[1] + neighbour_increment[1]
        ]:
            count = count + 1
    return count


def MakeArtLive(isWhiteUp):
    neighbour_increments = [(1, 1), (1, -1), (-1, 1), (-1, -1), (2, 0), (-2, 0)]
    to_flip = list()
    for coords in isWhiteUp:
        count = getNeighbourCount(coords, isWhiteUp)
        if isWhiteUp[coords] and count == 2:
            to_flip.append(coords)
        elif not isWhiteUp[coords] and (count == 0 or count > 2):
            to_flip.append(coords)
    for coords in to_flip:
        isWhiteUp[coords] = not isWhiteUp[coords]


def AddRequredTiles(isWhiteUp):
    neighbour_increments = [(1, 1), (1, -1), (-1, 1), (-1, -1), (2, 0), (-2, 0)]
    to_update = list()
    for coords in isWhiteUp:
        for neighbour_increment in neighbour_increments:
            new_coords = (
                coords[0] + neighbour_increment[0],
                coords[1] + neighbour_increment[1],
            )
            if new_coords not in isWhiteUp:
                to_update.append(new_coords)
    for coords in to_update:
        if coords not in isWhiteUp:
            isWhiteUp[coords] = True


def getCooordinatesFromPath(path):
    i = 0
    x = 0
    y = 0
    while i < len(path):
        if path[i] == "e":
            x = x + 2
            i = i + 1
        elif path[i] == "w":
            x = x - 2
            i = i + 1
        elif path[i : i + 2] == "nw":
            x = x - 1
            y = y + 1
            i = i + 2
        elif path[i : i + 2] == "ne":
            x = x + 1
            y = y + 1
            i = i + 2
        elif path[i : i + 2] == "sw":
            x = x - 1
            y = y - 1
            i = i + 2
        elif path[i : i + 2] == "se":
            x = x + 1
            y = y - 1
            i = i + 2
    return x, y


def main():
    f = open("../input/day_24_input")
    n_days = 100

    isWhiteUp = dict()
    for path in f:
        path = path.strip("\n")
        x, y = getCooordinatesFromPath(path)
        coord = (x, y)
        if coord in isWhiteUp:
            isWhiteUp[coord] = not isWhiteUp[coord]
        else:
            isWhiteUp[coord] = False
    for _ in range(0, n_days):
        AddRequredTiles(isWhiteUp)
        MakeArtLive(isWhiteUp)
    count = 0
    for key in isWhiteUp:
        if not isWhiteUp[key]:
            count = count + 1
    print(count)
    return count


if __name__ == "__main__":
    main()