LeetCode——Populating Next Right Pointers in Each Node II

標籤：leetcode

Follow up for problem "Populating Next Right Pointers in Each Node".

What if the given tree could be any binary tree? Would your previous solution still work?

Note:

• You may only use constant extra space.

For example,
Given the following binary tree,

         1       /        2    3     / \        4   5    7

After calling your function, the tree should look like:

         1 -> NULL       /        2 -> 3 -> NULL     / \        4-> 5 -> 7 -> NULL

原題連結：https://oj.leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/

題目：前一題的繼續，如果給定的是任意的二叉樹，前題的代碼還能用嗎？

思路：顯然，前一題不能用了。只好用層序遍曆。

public void connect(TreeLinkNode root) {if(root == null)return;TreeLinkNode parent = root,pre,next;while(parent != null){pre = null;next = null;while(parent != null){if(next == null)next = (parent.left == null) ? parent.right : parent.left;if(parent.left != null){if(pre != null){pre.next = parent.left;pre = pre.next;}elsepre = parent.left;}if(parent.right != null){if(pre != null){pre.next = parent.right;pre = pre.next;}elsepre = parent.right;}parent = parent.next;}parent = next;}}