[Leetcode]Populating Next Right Pointers in Each Node-优快云博客

本文介绍了一种用于完美二叉树（即所有叶子节点都在同一层且每个父节点都有两个子节点）中连接相邻节点的算法。该算法通过递归方式设置每个节点的next指针指向其右侧相邻节点，若无相邻节点则设置为NULL。实现仅使用常数额外空间。

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Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.

Initially, all next pointers are set to NULL.

Note:

You may only use constant extra space.
You may assume that it is a perfect binary tree (ie, all leaves are at the same level, and every parent has two children).

注意是完全二叉树！！！！我没有看Note想了半天没想好怎么求。。。。

 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 == NULL)
13         return ;
14         if(root->right!=NULL){
15             root->left->next=root->right;
16             if(root->next!=NULL){
17                 root->right->next=root->next->left;
18                 }
19             }
20         connect(root->left);
21         connect(root->right);
22         
23     }
24 };