Leetcode:binary Tree Zigzag level Order traversal

The subject also belongs to the deformation of the hierarchical traverse, the difference is that the method of its traversal is alternating, forming a zigzag curve form, as follows:

The code is as follows:

1 structTreeNode {2     intVal;3treenode*Left ;4treenode*Right ;5TreeNode (intx): Val (x), left (null), right (null) {}6 };7 8 voidSwap (vector<int> &Ivec)9 {Ten     inttemp =0; One     intLen =ivec.size (); A      for(inti =0; I < len/2; i + +) { -temp =ivec.at (i); -ivec.at (i) = ivec.at (len-1-i); theIvec.at (len-1-I.) =temp; -     } - } -  +Vector<vector <int> > Zigzaglevelorder (TreeNode *root) - { +vector<vector<int> >Tree_vector; Avector<int>Ivec; atQueue<treenode *>Tree_queue; -     if(NULL = =root) -         returnTree_vector; -  - Tree_queue.push (root); - Tree_queue.push (NULL); in     intNlevelcount =1; -      while(true) { toTreeNode *ptemp =Tree_queue.front (); + Tree_queue.pop (); -         if(Ptemp = =NULL) { the             if(nlevelcount%2==0) {//if the num is odd, swap the Ivec; * Swap (Ivec); $             }Panax Notoginseng Tree_vector.push_back (Ivec); - ivec.clear (); the             if(Tree_queue.empty ()) +                  Break; A Tree_queue.push (NULL); theNlevelcount + +; +         } -         Else { $Ivec.push_back (ptemp->val); $             if(ptemp->Left ) -Tree_queue.push (ptemp->Left ); -             if(ptemp->Right ) theTree_queue.push (ptemp->Right ); -         }Wuyi     } the     returnTree_vector; -}

Leetcode:binary Tree Zigzag level Order traversal