Implemented bfs

solver/bfs.go

@@ -1,9 +1,129 @@
 package solver
 
-import "maze-solver/maze"
+import (
+	"errors"
+	"fmt"
+	"maze-solver/maze"
+	"maze-solver/utils"
+	"strings"
+)
 
-type Bfs struct{}
-
-func (*Bfs) Solve(maze *maze.Maze) *maze.SolvedMaze {
-	return nil
+type BFSSolver struct {
+	solver
+	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)()
+
+	s.initVisited(m)
+
+	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)
+
+	// fmt.Printf("end.Coords: %v\n", end.Coords)
+	var err error
+	for current != end {
+		// fmt.Printf("current.Coords: %v\n", current.Coords)
+
+		s.visited[current] = 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)
+
+		// fmt.Println(s.queue)
+
+		current_history, err = s.queue.dequeue()
+		if err != nil {
+			panic(err)
+		}
+		current = current_history[len(current_history)-1]
+	}
+
+	// for i, node := range current_history {
+	// 	fmt.Printf("%v: %v\n", i, node.Coords)
+	// }
+
+	return &maze.SolvedMaze{
+		Maze:     m,
+		Solution: current_history,
+	}
+}
+
+func (s *BFSSolver) addIfNotVisited(node *maze.Node, current_history []*maze.Node) {
+	if !s.wasVisited(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)
+	}
 }