aoc2024/day-04/internal/one/neighbours.go

package one

type neighbour struct {
	x         int
	y         int
	direction int
}

func newNeighbour(direction, x, y int) neighbour {
	switch direction {
	case N:
		return neighbour{x, y + 1, direction}
	case NE:
		return neighbour{x + 1, y + 1, direction}
	case E:
		return neighbour{x + 1, y, direction}
	case SE:
		return neighbour{x + 1, y - 1, direction}
	case S:
		return neighbour{x, y - 1, direction}
	case SW:
		return neighbour{x - 1, y - 1, direction}
	case W:
		return neighbour{x - 1, y, direction}
	case NW:
		return neighbour{x - 1, y + 1, direction}
	default:
		return neighbour{}
	}
}

type neighbours struct {
	N  neighbour
	NE neighbour
	E  neighbour
	SE neighbour
	S  neighbour
	SW neighbour
	W  neighbour
	NW neighbour
}

func newNeighbours(x, y int) neighbours {
	return neighbours{
		newNeighbour(N, x, y),
		newNeighbour(NE, x, y),
		newNeighbour(E, x, y),
		newNeighbour(SE, x, y),
		newNeighbour(S, x, y),
		newNeighbour(SW, x, y),
		newNeighbour(W, x, y),
		newNeighbour(NW, x, y),
	}
}

func (n neighbours) all() [8]neighbour {
	return [8]neighbour{n.N, n.NE, n.E, n.SE, n.S, n.SW, n.W, n.NW}
}