Day 23 part one

from collections import defaultdict
maze_graph=defaultdict(set)
the_plan=[j.strip() for j in open("23.txt")]
directions={(0,-1):'^',(0,1):'v',(-1,0):'<',(1,0):'>'}
start=the_plan[0].find('.')
end=the_plan[-1].find('.')
pos=[[(start,0),(0,1),(start,1)]]
def avail(point,direction):
        direct=directions.copy()
        out=[]
        direct.pop((direction[0]*-1,direction[1]*-1))
        for d in direct:
            out.append([(point[0]+d[0],point[1]+d[1]),d])
        return list(filter(lambda x: the_plan[x[0][1]][x[0][0]]!='#',out))
def new_path_helper(list_of_pos):
     for i in list_of_pos:
        point,direction=i
        if the_plan[point[1]][point[0]]==directions[direction] or the_plan[point[1]][point[0]]=='.':
            yield i
def bfs():
    queue=[]
    ans=[]
    queue.append((1,maze_graph[(start,0)]))
    while queue:
        length,nodes=queue.pop(0)
        for node in nodes:
            l,point=node
            queue.append((length+l,maze_graph[point]))
        if len(nodes)==0:
            ans.append(length)
    return(ans)

for i in pos:
    origin,direction,point=i
    length=0
    while True:
        if point==(end,len(the_plan)-1):
                maze_graph[origin].add((length,point))
                break
        new=avail(point,direction)
        length+=1
        if len(new)==1:
            point,direction=new[0]
        else:
            maze_graph[origin].add((length,point))
            new=new_path_helper(new)
            for j in new:
                if [point,j[1],j[0]] not in pos:
                    pos.append([point,j[1],j[0]])
                else:
                    break
            break
print(max(bfs()))