algorithm - How to delete in a heap data structure? -


i understand how delete root node max heap procedure deleting node middle remove , replace root repeatedly until desired node deleted?

  1. is o(log n) optimal complexity procedure?

  2. does affect big o complexity since other nodes must deleted in order delete specific node?

actually, can remove item middle of heap without trouble.

the idea take last item in heap and, starting current position (i.e. position held item deleted), sift if new item greater parent of old item. if it's not greater parent, sift down.

that's procedure max heap. min heap, of course, you'd reverse greater , less cases.

finding item in heap o(n) operation, if know in heap, removing o(log n).

i published heap-based priority queue devsource few years back. see a priority queue implementation in c#. has removeat method described.

full source @ http://www.mischel.com/pubs/priqueue.zip


-

Comments

Post a Comment

Popular posts from this blog

java - UnknownEntityTypeException: Unable to locate persister (Hibernate 5.0) -

Image
in code below when try execute main.java getting exception: exception in thread "main" org.hibernate.unknownentitytypeexception: unable locate persister: com.np.vta.test.pojo.users @ org.hibernate.internal.sessionfactoryimpl.locateentitypersister(sessionfactoryimpl.java:792) @ org.hibernate.internal.sessionimpl.locateentitypersister(sessionimpl.java:2637) @ org.hibernate.internal.sessionimpl.access$2500(sessionimpl.java:164) @ org.hibernate.internal.sessionimpl$identifierloadaccessimpl.<init>(sessionimpl.java:2575) @ org.hibernate.internal.sessionimpl$identifierloadaccessimpl.<init>(sessionimpl.java:2562) @ org.hibernate.internal.sessionimpl.byid(sessionimpl.java:1044) @ org.hibernate.internal.sessionimpl.get(sessionimpl.java:955) @ com.app.test.main.main(main.java:20) but if uncomment cfg.addclass( users.class ).addresource( "com/np/vta/test/pojo/users.hbm.xml" ); code works fine. why not reading <mapping...
Read more

python - ValueError: empty vocabulary; perhaps the documents only contain stop words -

i'm using (for first time) scikit library , got error: valueerror: empty vocabulary; perhaps documents contain stop words file "c:\users\a605563\desktop\velibprojetpreso\traitementtwitterdico.py", line 33, in <module> x_train_counts = count_vect.fit_transform(filetweets) file "c:\python27\lib\site-packages\sklearn\feature_extraction\text.py", line 804, in fit_transform self.fixed_vocabulary_) file "c:\python27\lib\site-packages\sklearn\feature_extraction\text.py", line 751, in _count_vocab raise valueerror("empty vocabulary; perhaps documents contain stop words but don't understand why that's happening. import sklearn sklearn.feature_extraction.text import countvectorizer import pandas pd import numpy import unicodedata import nltk tweetsfile = open('tweets2015-08-13.csv', 'r+') f2 = open('analyzer.txt', 'a') print tweetsfile.readline() count_vect = countvectorizer(strip_accents='ascii...
Read more

ubuntu - collect2: fatal error: ld terminated with signal 9 [Killed] -

Image
i'm trying build precimonious on ubuntu 16.04.3 x64. allocated 1gb memory it. file structure looks like ~ |--- llvm/ |--- precimonious/ where llvm on version 3.0 mentioned @ https://github.com/corvette-berkeley/precimonious#requirement . followed steps on readme command make ended with ... llvm[1]: linking debug shared library libllvm-3.0.so collect2: fatal error: ld terminated signal 9 [killed] compilation terminated. ... i went through answers online , might because there's not enough memory perform link. memory usage the gcc version on machine gcc version 5.4.0 20160609 (ubuntu 5.4.0-6ubuntu1~16.04.4) , installed via apt-get install build-essential . fresh droplet created on digitalocean btw. appreciated. it memory exhaustion. sampling interval memory measurement not small enough covers exact point oom killer kicks in. depending on container/vm technology, may able set vm.overcommit_memory=2 before build, process not killed (but doing requires m...
Read more