java - Prevent Depth First Search Algorithm from getting stuck in an infinite loop ,8 Puzzle -


so code works basic 8 puzzle problems, when test harder puzzle configurations runs infinite loop. can please edit code prevent happening. note have included code prevents loops or cycles. tried including the iterative depth first search technique, did not work. can please review code. 

    /** implementation depth first search algorithm */ static boolean depthfirstsearch(string start, string out ){          linkedlist<string> open = new linkedlist<string>();     open.add(start);      set<string> visitedstates = new hashset<string>();      // prevent cyle or loop      linkedlist<string> closed = new linkedlist<string>();      boolean isgoalstate= false;      while((!open.isempty()) && (isgoalstate != true) ){          string x = open.removefirst();          system.out.println(printpuzzle(x)+"\n\n");         jtr.append(printpuzzle(x) +"\n\n");          if(x.equals(out)){               // if x goal             isgoalstate = true;             break;         }         else{                                                                 // generate children of x              linkedlist<string> children = getchildren(x);              closed.add(x);               // put x on closed             open.remove(x);             // since x in closed, take out open              //eliminate children of x if on open or closed ?             for(int i=0; i< children.size(); i++){                 if(open.contains(children.get(i))){                     children.remove(children.get(i));                 }                 else if(closed.contains(children.get(i))){                     children.remove(children.get(i));                 }             }               // put remaining children on left end of open                for(int i= children.size()-1 ; i>=0 ; i--){                 if ( !visitedstates.contains(children.get(i))) {   // check if state visited                        open.addfirst(children.get(i));              // add last child first, , on                         visitedstates.add(children.get(i));                 }             }          }     }          return true;     }

i suggest putting positions considering https://docs.oracle.com/javase/7/docs/api/java/util/priorityqueue.html priority based on how close being solved.

so take closest position off of queue, , add in of 1 move options there haven't yet been processed. repeat. you'll spent of time exploring possibilities close solved instead of moving randomly forever.

now question "how close solving it". 1 approach take sum of of taxicab distances between squares , need be. better heuristic may give more weight getting squares away corner in place first. if right, changing heuristic should easy.


Comments

Post a Comment

Popular posts from this blog

Is there a better way to structure post methods in Class Based Views -

i'm using class based views in django , never specify url in ajax calls , omit action parameter in form because know these requests go through post method of class based view. notice view - profile page make many requests depending on user updating on page - post method become convoluted , if/else mess example: def post(self, request, *args, **kwargs): # handle user changing available date if request.post.get('availabledate') != none: self.updateavailabledate(request) return jsonresponse({'result':'success'}) if request.post.get('newprojectname') != none: creative_user = creativeuserprofile.objects.get(id = request.user.id) project = project.create_project(creative_user, request.post['newprojectname']) project.save() return jsonresponse({'projectid': project.id }) if request.post.get('projectimage') != none , request.files['file']: proj...
Read more

performance - Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures? -

i'm doing micro-optimization on performance critical part of code , came across sequence of instructions (in at&t syntax): add %rax, %rbx mov %rdx, %rax mov %rbx, %rdx i thought had use case xchg allow me shave instruction , write: add %rbx, %rax xchg %rax, %rdx however, dimay found agner fog's instruction tables , xchg 3 micro-op instruction 2 cycle latency on sandy bridge, ivy bridge, broadwell, haswell , skylake. 3 whole micro-ops , 2 cycles of latency! 3 micro-ops throws off 4-1-1-1 cadence , 2 cycle latency makes worse original in best case since last 2 instructions in original might execute in parallel. now... cpu might breaking instruction micro-ops equivalent to: mov %rax, %tmp mov %rdx, %rax mov %tmp, %rdx where tmp anonymous internal register , suppose last 2 micro-ops run in parallel latency 2 cycles. given register renaming occurs on these micro-architectures, though, doesn't make sense me done way. why wouldn't register renamer ...
Read more

c# - Asp.net web api : redirect unauthorized requst to forbidden page -

im trying redirect unauthorized request forbidden page instead i'm getting forbidden page in response body , how can fix ? here's startup class : app.createperowincontext(storecontext.create); app.createperowincontext<applicationusermanager>(applicationusermanager.create); app.createperowincontext<applicationsigninmanager>(applicationsigninmanager.create); app.usecookieauthentication(new cookieauthenticationoptions { authenticationtype = defaultauthenticationtypes.applicationcookie, expiretimespan = timespan.fromdays(30), }); app.useexternalsignincookie(defaultauthenticationtypes.externalcookie); app.usetwofactorsignincookie(defaultauthenticationtypes.twofactorcookie, timespan.fromminutes(5)); app.usetwofactorrememberbrowsercookie(defaultauthenticationtypes.twofactorrememberbrowsercookie); the method im trying reach : [httpget] [authorize(roles = "admin")] public string getcurrentusername() { return userman...
Read more