題目

基本思路

1. 看到二叉樹我們就想到需要使用遞迴的思路了。
2. 注意遞迴之外的細節：正是這些細節完成了實際的邏輯求解 我們以2號結點為例:為了繁衍next結點,僅需要處理兩種微觀情況:

    case 1:  2 -> 3 :  
    Solution:       root.left.next  = root.right
    case 2:  2 -> 5 -> 6:  
    Solution:       root.right.next = root.next.left if root.next else None   
          2 ->
 
 3
         / \  / 
        4->5->6

實現程式碼

# Definition for binary tree with next pointer.
# class TreeLinkNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#         self.next = None

class Solution:
    # @param root, a tree link node
 

    # @return nothing
    def connect(self, root):
        if root and root.left:
            root.left.next = root.right
            if root.next:
                root.right.next = root.next.left
            else:
                root.right.next = None
            self.connect(root.left)
            self.
 
connect(root.right)