[Leetcode]Populating Next Right Pointers in Each Node II

最新推荐文章于 2021-09-24 12:05:40 发布

NoooName

最新推荐文章于 2021-09-24 12:05:40 发布

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分类专栏： Tree * 文章标签： leetcode python

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本文介绍了一种在常数额外空间下解决填充二叉树节点问题的方法，适用于任意二叉树结构。该解决方案通过一次遍历实现，不仅清晰易懂且效率高。

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

Populating Next Right Pointers in Each Node的扩展题~还是要求用常数空间，不过树不是完全二叉树~下面解法其实思路挺简单的，明白了的话写起来也会很顺手~

class Solution:
    # @param root, a tree node
    # @return nothing
    def connect(self, root):
        cur, head, prev = root, None, None
        while cur:
            while cur:
                if cur.left:
                    if prev:
                        prev.next = cur.left
                    else:
                        head = cur.left
                    prev = cur.left
                if cur.right:
                    if prev:
                        prev.next = cur.right
                    else:
                        head = cur.right
                    prev = cur.right
                cur = cur.next
            cur = head
            prev, head = None, None