> For the complete documentation index, see [llms.txt](https://liuyang89116.gitbook.io/my-leetcode-book/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://liuyang89116.gitbook.io/my-leetcode-book/chapter_3_binary_tree_bfs-_dfs/linkedlist-yu-binary-tree-xiang-hu-zhuan-huan/problem-116-populating-next-right-pointers-in-each-node.md).

# Problem 116: Populating Next Right Pointers in Each Node

> <https://leetcode.com/problems/populating-next-right-pointers-in-each-node/>

## 思路

* 题目已经强调了是 perfect tree
* 这道题的意思是，在原有的树的结构上，再把剩下的叶子根据条件也连起来。每次连的过程是由上边的“顶点”连它下面的左叶子和右叶子，如果顶点没有了 next，那么下边右子树将要直接指向 null。画个图就明白了。

```java
/**
 * Definition for binary tree with next pointer.
 * public class TreeLinkNode {
 *     int val;
 *     TreeLinkNode left, right, next;
 *     TreeLinkNode(int x) { val = x; }
 * }
 */
public class Solution {
    public void connect(TreeLinkNode root) {
        while (root != null) {
            TreeLinkNode node = root;
            while (node != null && node.left != null) {
                node.left.next = node.right;
                node.right.next = (node.next == null ? null : node.next.left);
                node = node.next;
            }
            root = root.left;
        }
    }
}
```