Can we get people to post code of simple, optimized implementations of the A* pathfinding algorithm, in every single language? This is mostly for fun and to play with what stackoverflow itself is capable of... although I actually am interested in getting an ActionScript 3 version of this. But the idea is that this "Question" will cont...
I've read in one of my AI books that popular algorithms (A-Star, Dijkstra) for path-finding in simulation or games is also used to solve the well-known "15-puzzle". Can anyone give me some pointers on how I would reduce the 15-puzzle to a graph of nodes and edges so that I could apply one of these algorithms? If I were to treat each no...
Hello, I'm looking at definitions of the A* path-finding algorithm, and it seems to be defined somewhat differently in different places. The difference is in the action performed when going through the successors of a node, and finding that a successor is on the closed list. One approach (suggested by Wikipedia, and this article) say...
I am working on a roguelike in my (very little) free time. Each level will basically be a few rectangular rooms connected together by paths. I want the paths between rooms to be natural-looking and windy, however. For example, I would not consider the following natural-looking: B X X X ...
Hi all, I need an Erlang implementation of the A* search algorithm. Any pointers? ...
I'm working on a game that uses A-star (A*) for path finding but I've come to a point where by I have some objects that are larger than a single grid square. I'm running on a grid of 16*16px. wall segments are 16*16 and so make a single square impassable. Some of my baddies are 32*32 and so they need to check that a gap is at least 2 gr...
A-star is used to find the shortest path between a startnode and an endnode in a graph. What algorithm is used to solve something were the target state isn't specifically known and we instead only have a criteria for the target state? For example, can a sudoku puzzle be solved with an Astar-like algorithm? We dont know how the endstate ...
I have implemented the A* algorithm in AS3 and it works great except for one thing. Often the resulting path does not take the most “natural” or smooth route to the target. In my environment the object can move diagonally as inexpensively as it can move horizontally or vertically. Here is a very simple example; the start point is marked...
When is using a std::set more efficient (w.r.t. time) than using a std::vector along with make_heap/push_/pop_ for the priority queue in an A* operation? My guess is that if the vertices in the open list are small, using a vector is a better option. But does anyone have experience with this? ...
I am confused about the terms overestimation/underestimation. I perfectly get how A* algorithm works, but i am unsure of the effects of having a heuristic that overestimate or underestimate. Is overestimation when you take the square of the direct birdview-line? And why would it make the algorithm incorrect? The same heuristic is used f...
Hi all. I asked a question some time ago on java 2d pathfinding... http://stackoverflow.com/questions/735523/pathfinding-2d-java-game The game im developing is based on the idea of theme hospital. The chosen answer from my question, A* pathfinding, the link was awesome, and very helpful. I'm eventually getting to implement this into my ...
I'm in the process of developing a simple 2d grid based sim game, and have fully functional path finding. I used the answer found in my previous question as my basis for implementing A* path finding. (http://stackoverflow.com/questions/735523/pathfinding-2d-java-game). To show you really what I'm asking, I need to show you this video s...
I have written an implementation of the A* search algorithm. The problem is that the heuristic I'm currently using only works accurately on square grids. As my map is isometric, the heuristic doesn't take into account actual the layout of the map and thus, the distance between cells. Update: After extensive logging and analysis (read as...
I was looking at what the guys in the Mario AI Competition have been doing and some of them have built some pretty neat Mario bots utilizing the A* (A-Star) Pathing Algorithm. (Video of Mario A* Bot In Action) My question is, how does A-Star compare with Dijkstra? Looking over them, they seem similar. Why would someone use one ove...
The 8-puzzle is a square board with 9 positions, filled by 8 numbered tiles and one gap. At any point, a tile adjacent to the gap can be moved into the gap, creating a new gap position. In other words the gap can be swapped with an adjacent (horizontally and vertically) tile. The objective in the game is to begin with an arbitrary config...
I understand how to use a breadth first search and A* in a tree structure, but given the following graph, how would it be implemented? In other words, how would the search traverse the graph? S is the start state Graph Here ...
I've got a pretty big A* pathfinding function that gets called frequently and has to be put in another thread because otherwise it will make my game stutter. I come from a Java background, and recently read a discussion about the speed of HashMap's (essentially the equivalent of NSDictionary) and the different implementations you can use...
Is there a good way to do a multithreaded A* search? Single threaded is fairly easy, as given in (for example) Artificial Intelligence: A Modern Approach, but I have not come across a good multithreaded version. Assume a sane language like Java or C# or Lisp where we have thread pools and work blocks, and of course garbage collection. ...
Wikipedia says on A* complexity the following (link here): More problematic than its time complexity is A*’s memory usage. In the worst case, it must also remember an exponential number of nodes. I fail to see this is correct because: Say we explore node A, with successors B, C, and D. Then we add B, C, and D to the list of ...
I find the algorithm description in AIMA (Artificial Intelligence: A Modern Approach) is not correct at all. What does 'necessary' mean? What is the memory limit? The queue size or processed nodes? What if the current node has no children at all? I am wondering if this algorithm itself is correct or not. Because I searched the Internet ...