我的深度拳头搜索路线查找速度非常慢

Question

这只是固有的，因为我的状态图的分支因子是4（因此在Iterative-Deepening的任何阶段它将是4 ^ k并且比以前指数级慢？）

或者有什么我错过了吗？

这是我的DFS方法：

    /**
 * CONTAINS Deja-Vu checker!
 */                                                                                              
private static Node depthFirst(Node start, String goal, ArrayList<Node> visited, int depth)
{      
    //END-case
    if (start.getConfig().equals(goal)){
        return start;
    }
    else if (depth == 0){
        //IF DEPTH REACHED BUT NOT FOUND GOAL
        return null;
    }

    //main sequence
    ArrayList<Node> neighbours = start.getNeighbours();
    for (Node neighbour : neighbours){
        //Deja-Vu check
        if (!(visited.contains(neighbour))){
           visited.add(neighbour);
           //my version of linked list
           start.append(depthFirst(neighbour, goal, visited, (depth-1)));
           //FALSE-PATH DENIAL
           if (start.route != null){
                return start;
           }
        }
    }
    //false path
    return null;
}

这包含在我的Iterative Deepening方法中：

    /**
 * ASSUMES limit is 1000
 */
private static Node IterativeDeepening(Node start, String goal)
{
    Node route;

    for (int depth = 1; (depth < 1000); depth++){               
        route = depthFirst(start, goal, (new ArrayList<Node>()), depth);
        if (route != null){
            return route;
        }
    }

    //if all routes are null
    return null;
}