aoc2024/day-15/internal/two/explore.go

package two

import (
	log "github.com/sirupsen/logrus"

	orderedmap "github.com/wk8/go-ordered-map/v2"
)

func exploreDFS(graph *graph, next point, dir direction, stack *stack) (*stack, bool) {
	ns := neighbours(next)

	log.Debug(string(graph.valueAt(ns[dir])))

	switch graph.valueAt(ns[dir]) {
	case '#':
		return nil, false
	case '.':
		return stack, true
	case '[', ']':
		stack.Push(ns[dir])
	}

	return exploreDFS(graph, ns[dir], dir, stack)
}

func exploreBFS(graph *graph, dir direction) (*orderedmap.OrderedMap[point, struct{}], bool) {
	queue := newQueue()
	queue.Enqueue(graph.robot)
	visited := make(map[point]struct{})
	om := orderedmap.New[point, struct{}]()

	for !queue.IsEmpty() {
		current := queue.Dequeue().(point)

		_, ok := visited[current]
		if ok {
			continue
		}
		visited[current] = struct{}{}

		ns := neighbours(current)
		switch graph.valueAt(ns[dir]) {
		case '.':
			if graph.valueAt(current) == '@' {
				return om, true
			}
		case '#':
			return om, false
		case '[', ']':
			nextDirections := []direction{dir}

			if graph.valueAt(ns[dir]) == '[' {
				switch dir {
				case N:
					nextDirections = append(nextDirections, NE)
				case S:
					nextDirections = append(nextDirections, SE)
				}
			} else if graph.valueAt(ns[dir]) == ']' {
				switch dir {
				case N:
					nextDirections = append(nextDirections, NW)
				case S:
					nextDirections = append(nextDirections, SW)
				}
			}

			for _, nextDirection := range nextDirections {
				log.Debugf("adding %s to the queue", string(graph.valueAt(ns[nextDirection])))
				queue.Enqueue(ns[nextDirection])
				_, ok := om.Get(ns[nextDirection])
				if !ok {
					om.Set(ns[nextDirection], struct{}{})
				}
			}
		}
	}

	return om, true
}