package solver import ( "errors" "fmt" "maze-solver/maze" "maze-solver/utils" "strings" ) type BFSSolver struct { queue *Queue } type Queue struct { head, tail *Element } type Element struct { prev, next *Element value []*maze.Node } func (q *Queue) enqueue(v []*maze.Node) { prev_last := q.tail new_elem := &Element{ prev: prev_last, next: nil, value: v, } if prev_last != nil { prev_last.next = new_elem } q.tail = new_elem if q.head == nil { q.head = new_elem } } func (q *Queue) dequeue() ([]*maze.Node, error) { if q.head == nil { return nil, errors.New("Can't dequeue and empty queue") } ret := q.head.value q.head = q.head.next if q.head != nil { q.head.prev = nil } else { q.tail = nil } return ret, nil } func (q Queue) String() string { var ret strings.Builder i := 0 for history := q.head; history != nil; history = history.next { ret.WriteString(fmt.Sprintf("%v: %v\n", i, history_str(history.value))) i++ } return ret.String() } func history_str(history []*maze.Node) string { var ret strings.Builder for _, node := range history { ret.WriteString(fmt.Sprintf("%v ", node.Coords)) } return ret.String() } func (s *BFSSolver) Solve(m *maze.Maze) *maze.SolvedMaze { defer utils.Timer("BFS algorithm", 2)() current, end := m.Nodes[0], m.Nodes[len(m.Nodes)-1] s.queue = &Queue{ head: nil, tail: nil, } current_history := make([]*maze.Node, 0, len(m.Nodes)) current_history = append(current_history, current) var err error for current != end { current.Visited = true s.addIfNotVisited(current.Down, current_history) s.addIfNotVisited(current.Left, current_history) s.addIfNotVisited(current.Right, current_history) s.addIfNotVisited(current.Up, current_history) current_history, err = s.queue.dequeue() if err != nil { panic(err) } current = current_history[len(current_history)-1] } return &maze.SolvedMaze{ Maze: m, Solution: current_history, } } func (s *BFSSolver) addIfNotVisited(node *maze.Node, current_history []*maze.Node) { if !visited(node) { new_history := make([]*maze.Node, len(current_history)+1) copy(new_history, current_history) new_history[len(current_history)] = node s.queue.enqueue(new_history) } }