leetcode Populating Next Right Pointers in Each Node II

最新推荐文章于 2021-09-24 12:05:40 发布

原创最新推荐文章于 2021-09-24 12:05:40 发布 · 674 阅读

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本文探讨了如何在任意二叉树中填充每个节点的Next指针，使其指向同层的下一个节点。解决方案需确保仅使用常数额外空间，并通过递归方式实现了这一目标。

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,

After calling your function, the tree should look like:

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

/**
 * 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) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(root==null) return;
        TreeLinkNode current=null,tmp=null;
        while(root!=null){
            if(root.left!=null){
                if(tmp==null) tmp=root.left;
                if(current==null) current=root.left;
                else{
                  current.next=root.left;
                  current=root.left;
                }
            }
            if(root.right!=null){
                if(tmp==null) tmp=root.right;
                if(current==null) current=root.right;
                else{
                  current.next=root.right;
                  current=root.right;                    
                }
            }
            root=root.next;
        }
        connect(tmp);
    }
}