Got two methods:  public void getBalance(){     balance(root); }  private void balance(TreeNode node) {       if (node != null &amp;&amp; node.left != null) {         balance(node.left);         balance(node.right);         System.out.println(node.left);         //sout work fine     } }   need to return value from balance();  if I change return value from void to TreeNode, and change code      private TreeNode balance(TreeNode node) {       if (node != null &amp;&amp; node.left != null) {         balance(node.left);         balance(node.right);         return node.left;      }     return balance(node); }   return sStackOverflowError Exception.  I need to return node left from this method.  Please help.
What is a StackOverflowError, what causes it, and how should I deal with them?
How would I use Takeown to take ownership of all folders on one drive? I've been looking all over for a proper explanation of how to delete photos from the device (nexus 5) to reclaim some space, while being sure that the pictures are still in the Google+ backup. Unfortunatley i have not found one, other than "wild claims" it works somehow, while other say it does not. Plus deleting photos via the Pictures app actually warns you (now?) that it will delete the backed up copies too. Do i have to delete them in the Gallery app?  I did delete some photos recently, and i was quite sure they ware still backed up (still showed up on the Google+ website) but looking now i see they are in the trash in the device.  Is there really no way to be able to know for sure if the pictures are backed up savely while i can delete them from the device?  Alternatively i'm also open for alternative solutions to this problem, or i just go back to the "good old copy and paste when plugging the phone". Suppose $\mu(X)&lt;\infty$. Show that if $\ f\in\ L^q(X,\mu)$ for some $1\le q&lt;\infty$ then $\ f\in\ L^r(X,\mu)$ for $1\le r&lt;q$   In the solution the assistant wrote this:  If $1\le r&lt;q$ then $q/r\ge 1$. Let p be the dual exponent to $q/r$ (i.e. $\frac{1}{q/r}+\frac{1}{p}=1)$  then by Hölder Inequality  $\int_{X}|f|^rd\mu\le\underbrace{(\int_{X}|f|^qd\mu)^{r/q}}_{??????}(\int_X1^pd\mu)^{1/p}&lt;\infty$  for me the middle part doesn't make sense (it is not the hölder inequality) can somebody show it ?  instead of this can't we say (only in this case) that   $\int_{X}|f|^rd\mu\le (\int_{X}|f|d\mu)^r$ then  $(\int_{X}|f|d\mu)^r\le ((\int_{X}|f|^qd\mu)^{1/q}(\int_X1^pd\mu)^{1/p})^r&lt;\infty$  ? How exactly do I install Minecraft Mods and what is Forge? Can I have multiple primary keys in a single table? Software to draw illustrative figures in papers I would like to have suggestions of good software for drawing illustrations in research papers. I already know about , but this works only on Linux and is at times, clunky when it comes to text. Moreover the resolution is not always perfect making it difficult to manoeuvre the objects. Besides it is tough to learn and master, with all its weird click procedures.   I would love to know about better alternatives. Not talking about graphs here, just block diagrams and explanatory illustrations. Modular exponentiation by repeated squaring I am new to salesforce. I dont have coding background. Please let me know bst way to learn apex coding? Is it permissible to use somebody else's words (without quotations) to describe a concept once their work is cited? Quite often one comes across a really succinct and precise explanation of a concept. I'm wondering if it is permissible to use this explanation verbatim, if the source work is cited in your paper (next to the explanation)? What's in question here is at most 3 sentences. Chaining the Imperius curse What would happen if a wizard w successfully casts the Imperius curse on a equally powerful wizard a and then order him to cast the same curse back on w?  Follow-up questions.  It is established that casting the curse can be done .  What would happen in the case of a chain of casts that would hit back the original wizard? w-&gt;a-&gt;b-&gt;c-&gt;w  The original wizard could rather command the last wizard c, in the chain, to curse his first target instead. w-&gt;a-&gt;b-&gt;c-&gt;a wich would create a loop of a-&gt;b-&gt;c-&gt;a...  In what kind of limbo would wizards a, b and c exist in?  ( for the sake of simplicity, we can assume that every curse target is not very good at resisting the curse ) Simple question:     My apples and orange are wrong   or     My apples and orange is wrong   I am not a native English speaker, and I am having some trouble choosing between plural are or singular is for that kind of example. Is there a convenient way to import a schema into Oracle 11gR2 using a single new or different tablespace than where the data originated?  As an example, I have exported BLOG_DATA from OLDDB, where all user data is stored in the USERS tablespace.   On NEWDB, I would like to import the BLOG_DATA schema, but store the user objects in the BLOG_DATA tablespace, created specifically for this user.   I have created the BLOG_DATA user, created the BLOG_DATA tablespace and set it as the default tablespace for that user and added an appropriate unlimited quota.  CREATE TABLESPACE blog_data DATAFILE SIZE 1G;  CREATE USER blog_data IDENTIFIED BY secretpassword DEFAULT TABLESPACE blog_data QUOTA UNLIMITED ON blog_data;  GRANT connect,resource TO blog_data   The schema was exported from OLDDB with something like  exp blog_data/secretpassword@OLDDB file=blog_data.dmp    After reading Phil's excellent answer below, I found myself wondering:   Since data has no other place to go than the default tablespace - the only tablespace the user has a quota on - will this effectively force imp to put all user objects in that default tablespace?  imp blog_data/secretpassword@NEWDB file=blog_data.dmp   Would this then place the entire blog_data schema in the blog_data tablespace on NEWDB? Is there any reason why this wouldn't work or that I would run into problems with certain objects etc?  update:  I did a quick test and found this to be the case. Imp places objects in the default tablespace for that user, provided it can't place it in the original tablespace (eg. the tablespace does not exist). Full explanation:   Still, I suppose that using Data Pump like Phil suggests might be the preferred option. What causes "java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute"? Can't compile any c/ c++ program, linker problem It's my second post here, i have a huge problem which prevents me to study so i have to fix it as soon as it's possible ! My gcc was working fine and i had to work on FairThreads (in C). I downloaded the following archive :  As you can see, in /src there's a makeFile, i replaced the second line which was : LIB_DIR     = ../lib  by LIB_DIR     =  /usr/bin/ld and i compiled the makeFile by the command &quot;make&quot; And now, i cannot compile any c/c++ program anymore. Even a hello world program. I got the following error message on the terminal for every compiling attempt : /usr/bin/ld: 2: /usr/bin/ld: Syntax error: newline unexpected collect2: error: ld returned 2 exit status  I have found on the net this solution but it doesn't work for me : sudo apt-get autoremove binutils     sudo apt-get install binutils  I also tried to reinstall gcc, when executing : sudo apt-get purge gcc   i got : Des erreurs ont été rencontrées pendant l'exécution :   linux-firmware   linux-image-generic-hwe-18.04   linux-generic-hwe-18.04 E: Sub-process /usr/bin/dpkg returned an error code (1)  but when i trie a gcc --version it tells me that it is not found. So when i execute the command to reintall it : sudo apt-get install gcc   i also get : Des erreurs ont été rencontrées pendant l'exécution :  linux-firmware  linux-image-generic-hwe-18.04  linux-generic-hwe-18.04  linux-image-5.4.0-72-generic  initramfs-tools E: Sub-process /usr/bin/dpkg returned an error code (1)  but gcc --version tellls that it's installed. Finally, when i trie to compile a program, i got : /usr/bin/ld: 2: /usr/bin/ld: Syntax error: newline unexpected collect2: error: ld returned 2 exit status  I hope that i explained well, and i'll get a solution for this :/, as a computer science student, i can't do anything without gcc :( EDIT 1 : When i try to remove bin/ld by executing : sudo rm -fr /usr/bin/ld;sudo apt-get install --reinstall binutils  i got : Des erreurs ont été rencontrées pendant l'exécution :  linux-firmware  linux-image-generic-hwe-18.04  linux-generic-hwe-18.04  linux-image-5.4.0-72-generic  initramfs-tools E: Sub-process /usr/bin/dpkg returned an error code (1)  and this particular error message : WARNING: no ldd around - install libc-bin  EDIT : I have installed ldd by the command : sudo apt-get install libc-bin  still no changes... What is Ruby's double-colon `::`? std::auto_ptr to std::unique_ptr Proof for maximal ideals in $\mathbb{Z}[x]$ I have been trying to prove the following theorem:      Every maximal ideal in $\mathbb{Z}[x]$ has the form $(p, f(x))$ where $p$ is prime integer and $f$ is primitive integer polynomial that is irreducible modulo $p$.    Idea: I tried to establish a homomorphism $\phi: \mathbb{Z}[x] \rightarrow \mathbb{F}$. Since $\mathbb{F}$ is a field it has characteristic $p$ and so integer prime p are mapped to 0 in $\mathbb{F}$. Hence $p\in \ker \phi$. Next we consider $\phi': \mathbb{Z}[x] \rightarrow \mathbb{Z_p}[x]$ and pick an arbitrary maximal ideal $M\in \mathbb{Z}[x]$. So, $\phi'(M)$ is maximal as long as $p \in M$ by correspondence. But now I am stuck at this stage and do not know how to proceed. I guess we might have to use primitivity given in problem but dont know how. Pulling a CSV file from website into QGIS with ability to automatically refresh? I have Ubuntu 12.04 LTS. I need the correct output because I edited it because it wasn't working but it has only made it worse. Searching by user id in Android app only shows questions, no answers I have a Samsung Galaxy S3. Android version 4.3  I downloaded the official StackExchange app today. I am not able to view post related to android tag from my profile. I tried refreshing also  Snap     Edit:  However i am able to see one post for the relevant from the drop down list    Edit 2:  I tried what Steven V suggested. However it's the same.    I tried for a different user its the same.