aoc2023/day-16/two.go

package main

// returns the number of unique nodes (reducing multiple nodes with different directions to one)
func uniqueNodes(move *mover) int {
	uniqueCoords := []coords{}
	for _, node := range move.nodes {
		if !coordInCoords(node.coords, uniqueCoords) {
			uniqueCoords = append(uniqueCoords, node.coords)
		}
	}
	return len(uniqueCoords)
}

// spawn invoked a single runner with a single mover
func spawn(i, j, direction int, lines []string) int {
	m := newMover(newNode(i, j, direction))
	runner(m, lines)
	return uniqueNodes(m)
}

// two returns the highest energized value for any beam spawn point/direction
func two(lines []string) int {
	res := 0
	n := 0

	var x = 0
	for x < len(lines[0]) {
		n = spawn(x, 0, S, lines)
		if n > res {
			res = n
		}
		n = spawn(x, len(lines[0])-1, N, lines)
		if n > res {
			res = n
		}
		x++
	}

	var y = 0
	for y < len(lines) {
		n = spawn(0, y, E, lines)
		if n > res {
			res = n
		}
		n = spawn(len(lines[0])-1, y, W, lines)
		if n > res {
			res = n
		}
		y++
	}

	return res
}