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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
题目分析：和Populating Next Right Pointers in Each Node那题比本题不保证是满二叉树，因此如果用那题的做法将会非常麻烦，需要判断很多null的情况，换个角度思考，模拟一下树层次遍历的过程，给每一层加一个头结点，就可以解决这个问题。1ms
/*** 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) {TreeLinkNode lastNode = root;while (lastNode != null) {TreeLinkNode cur = new TreeLinkNode(0);TreeLinkNode curHead = cur;while (lastNode != null) {if (lastNode.left != null) {cur.next = lastNode.left;cur = cur.next;}if (lastNode.right != null) {cur.next = lastNode.right;cur = cur.next;}lastNode = lastNode.next;}lastNode = curHead.next;}}
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