Given a binary tree
struct TreeLinkNode {
TreeLinkNode *left;
TreeLinkNode *right;
TreeLinkNode *next;
}
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:
Example:
Given the following perfect binary tree,
1 / 2 3 / \ / 4 5 6 7
After calling your function, the tree should look like:
1 -> NULL / 2 -> 3 -> NULL / \ / 4->5->6->7 -> NULL
产生额外内存开销的方法（BFS）：
/** * 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) { if(root == null){ return; } Queue<TreeLinkNode> queue = new LinkedList<>(); queue.offer(root); while(!queue.isEmpty()){ int size = queue.size(); for(int i=0; i<size; i++){ TreeLinkNode curNode = queue.poll(); if(i<size-1){ TreeLinkNode next = queue.peek(); curNode.next = next; } if(curNode.left != null) queue.offer(curNode.left); if(curNode.right != null) queue.offer(curNode.right); } } } }
LeetCode-Microsoft-Populating Next Right Pointers in Each Node
原文：https://www.cnblogs.com/incrediblechangshuo/p/8970750.html