leetcode：117。各ノードIIに次の右ポインタを入力する

Leetcode 117 Populating Next Right Pointers Each Node Ii

困難

中。

問題

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: You may only use constant extra space. Recursive approach is fine, implicit stack space does not count as extra space for this problem. 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

交流

# Definition for binary tree with next pointer. # class TreeLinkNode(object): # def __init__(self, x): # self.val = x # self.left = None # self.right = None # self.next = None class Solution(): def connect(self, root): dummy = TreeLinkNode(-1) node = dummy while root: while root: node.next = root.left node = node.next or node node.next = root.right node = node.next or node root = root.next root, node = dummy.next, dummy