Populating Next Right Pointers in Each Node II

 1 /**
 2  * Definition for binary tree with next pointer.
 3  * struct TreeLinkNode {
 4  *  int val;
 5  *  TreeLinkNode *left, *right, *next;
 6  *  TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     void connect(TreeLinkNode *root) {
12         if(!root) return;
13         
14         TreeLinkNode pre(-1); //previous node in the level
15         for(TreeLinkNode* current = root, *move = ⪯ current; current = current->next){
16             if(current->left){
17                 move->next = current->left;
18                 move = move->next;
19             }
20             if(current->right){
21                 move->next = current->right;
22                 move = move->next;
23             }
24             //current = current->next; //children of the current node have been dealt, move to the next node in the level
25         }
26         root = pre.next; //assign the first node in the next level to root and begin the new recursion
27         connect(root);
28     }
29 };